compressionn.

/kəmˈprɛʃən/

Forms: Also Middle English–1500s comprysion, comprission.

Etymology: < French compression, < Latin compressiōn-em , noun of action, < comprimĕre (participial stem compress- ): see compress v.

a. The action of compressing; pressing together, squeezing; forcing into a smaller compass; condensation by pressure.

ΘΚΠ

the world > space > extension in space > reduction in size or extent > [noun] > compression or constriction

compressing1398

compressionc1400

constrictionc1400

spanning1527

coarctation1540

restriction1580

choking1635

coarction1782

the world > matter > constitution of matter > density or solidity > [noun] > becoming or making dense or solid > by compaction or compression

compaction1398

compressionc1400

constipation1603

compressure1644

compacting1697

the world > matter > physics > mechanics > force > [noun] > pressure > compression

compressionc1400

c1400 Lanfranc's Cirurg. (MS. A) 23 A gristil..haþ sixe helpingis [uses]..þo .ij. þat þe harde schulde not hirte þe neische, nameli in þe tyme of compressioun [v.r. comprission], & in þe tyme of smytinge.

?1592 Trag. Solyman & Perseda sig. C3 Why what is iewels, or what is gould but earth, An humor knit together by compression.

1597 P. Lowe Art Chirurg. (1634) 58 Cast forth by the great dilation of the heart or else by the great comprysion thereof.

1659 J. Leak tr. I. de Caus New Inventions Water-works Pref. 3 Water cannot be forced by compression to be contained in less space then its Natural extension.

1774 O. Goldsmith Hist. Earth II. 59 The infant itself has milk in its own breasts, which may be squeezed out by compression.

1863 J. Tyndall Heat (1870) i. §7. 6 To consider the development of heat by compression.

b. Constraint, coercion.

ΘΚΠ

society > authority > subjection > obedience > compulsion > [noun]

needeOE

distressc1384

force1387

stressc1390

artingc1400

coactionc1400

constrainauncec1400

compulsion1462

enforcement1477

coercion1495

forcement1524

enforcing1531

strain1532

constraint1533

coercement1592

constrainment1593

duress1596

compulse1616

obligement1641

cogency1702

coercive control1827

steamrolling1879

compression1880

1880 Church Times 10 Nov. 779 Dwelling chiefly upon the causes of modern infidelity in France, [he] does not hesitate to ascribe it in a great measure to the compression exercised by Louis XIV.

c. figurative. The condensation of thought or language.

ΘΚΠ

the world > the universe > planet > [noun] > part of planet > polar flattening

polar flattening1784

compression1820

society > leisure > the arts > literature > style of language or writing > conciseness > [noun] > compressed quality > compression

contraction1655

condensation1798

compression1820

compressure1833

1820 M. R. Mitford in A. G. L'Estrange Life M. R. Mitford (1870) II. v. 92 Great as our merits might be in some points, we none of us excelled in compression.

1850 A. Jameson Legends Monastic Orders Pref. p. xv The difficulty of compression has been the greatest of all my difficulties.

d. In a steam-engine, the reduction in volume of the steam left in the cylinder after the exhaust is closed towards the end of the exhaust stroke.

ΘΚΠ

society > occupation and work > equipment > machine > machines which impart power > engine > steam engine > [noun] > steam > reduction in

compression1859

1859 W. J. M. Rankine Man. Steam Engine iii. iii. 420 Compression, or cushioning, is effected by closing the eduction valve before the end of the return stroke.

1871 Eng. Mechanic 7 July 377 The relative ratios of compression and of expansion during the exhaust and steam strokes.

1883 M. N. Forney Catech. Locomotive 44 The steam-port is also closed to the exhaust, or compression, as it is called.

1886 Sci. Amer. 54 56/2 ‘Compression’ [in a steam-engine] is confinement of steam by closing the exhaust opening before the return stroke is ended, thus causing a rise in pressure.

1913 W. R. King Steam Engin. v. 105 This compression provides an elastic cushion of steam which absorbs the momentum of the reciprocating parts of the engine and brings them to rest without shock.

1936 E. A. Phillipson Steam Locomotive Design x. 317 The compression point should advance when the engine is running..at high piston speeds, in order that sufficient cushioning may be available to counteract the greatly augmented inertia forces then set up by the reciprocating masses.

e. In an internal-combustion engine, the reduction in volume of the mixture of fuel and air drawn into the cylinder; also, the value or effectiveness of this as a factor affecting the running of the engine.

ΘΚΠ

society > occupation and work > equipment > machine > machines which impart power > engine > internal-combustion engine > [noun] > fuel or air mixture

stratified charge1886

compression1887

stratification1914

swirl1926

secondary air1931

squish1934

1887 D. Clerk Gas Engine (ed. 2) vii. 197 When compression is completed the igniting valve acts and the explosion impels the piston.

1887 Encycl. Brit. XXII. 523/1 Compression did not in his case increase what may be called the theoretical thermodynamic efficiency.

1907 R. B. Whitman Motor-car Princ. xi. 193 Other losses of compression may be due to a cracked piston.

1908 Westm. Gaz. 20 Aug. 4/2 It has been aptly stated that the carburetter is the lungs of the internal-combustion engine, and in a similar way the compression may be said to represent the muscle.

1912 Motor Man. (ed. 14) 227 No engine ever pulled well with feeble compression.

1963 D. V. W. Francis Morris Engines i. 7 It should be possible to feel a good and even compression for all the cylinders.

f. The process of subjecting to compressed air in an air-lock.

ΚΠ

1906 Westm. Gaz. 27 Jan. 10/1 The men who controlled the airlocks, and were subjected to compression and decompression every few minutes, were in no case affected.

a. A state or condition of being compressed.

ΘΚΠ

the world > space > extension in space > reduction in size or extent > [noun] > compression or constriction > state or condition

compression1603

astringency1669

comprehension1712

1603 J. Florio tr. M. de Montaigne Ess. i. xx. 43 Those instruments..have their proper compressions and dilatations, [etc.].

1771 H. Mackenzie Man of Feeling (1886) 37 His fingers lost their compression.

1849 R. I. Murchison Siluria ix. 204 Every variety of distortion and compression.

1871 J. Tyndall Fragm. Sci. (ed. 6) I. ix. 300 The moraine is in a state of longitudinal compression.

b. of thought, language, or writing.

ΘΚΠ

society > leisure > the arts > literature > style of language or writing > conciseness > [noun] > compressed quality

compression1759

tabloidization1926

1759 S. Johnson Idler 18 Aug. 257 Best pleased with involution of argument and compression of thought.

1823 J. Badcock Domest. Amusem. p. vi The state of compression in which it [the treatise] now appears.

c. figurative. Straitened or repressed condition, under the operation of trouble, tyranny, or the like.

ΘΚΠ

the world > action or operation > adversity > [noun] > oppression, persecution, or affliction

threat971

constraintc1374

oppressiona1382

pressurec1384

aggrievancea1400

thronga1400

oppress1488

aggrievement1646

compression1759

society > authority > subjection > [noun] > to oppressive rule

yokeeOE

nitheringeOE

underputtingc1440

servitude?1473

compression1816

downtroddenness1868

1759 J. Mills tr. H. L. Duhamel du Monceau Pract. Treat. Husbandry ii. ii. 194 The state of compression which those in the common way were in after harvest.

1816 T. Jefferson Writings (1830) IV. 280 That nation is too high-minded..to remain quiet under its present compression.

1879 F. W. Farrar Life & Work St. Paul II. ix. xxxiii. 101 That previous letter..had been written in much tribulation and compression of heart.

3. compression of the poles: the flattening of a planet at the poles, making it an oblate spheroid.

ΚΠ

1814 J. Playfair Outl. Nat. Philos. II. i. ix. 179 The compression of Jupiter amounts to a fourteenth part of his longer diameter.

1849 M. Somerville On Connexion Physical Sci. (ed. 8) iv. 34 Of ascertaining the compression of Jupiter's spheroid.

†4. Surgery.

a. A compress. Obsolete. rare.

ΘΚΠ

the world > health and disease > healing > medical appliances or equipment > equipment for treating wound or ulcer > [noun] > poultice, plaster, or compress

plasterOE

clydec1325

emplastera1382

entretea1400

pottagea1400

poulticea1400

faldellac1400

treatc1400

Gratia Dei?a1425

magdaleon?a1425

strictorya1425

grace of Godc1450

emplastrum?1541

malagma?1541

sparadrap1543

spasmadrap?a1547

plasture?1550

mustard plaster1562

cataplasm1563

oint-plaster1578

quilt1583

compress1599

compression1599

diachylum-plaster1599

pulment1599

pulvinar1599

frontlet1600

sinapism1601

epithemation1615

diapalma1646

opodeldoc1646

attraction1656

treacle plaster1659

melilot emplaster1676

stay1676

oxycroceum1696

melilot plaster1712

adhesive1753

bag1753

mustard poultice1765

soap plaster1789

water dressing1830

poor man's plaster1833

compressor1851

spongiopiline1851

vinegar-poultice1854

water-strapping1854

pitch-plaster1858

jacket poultice1862

mustard leaf1869

mustard paper1874

piline1874

plaster-mull1890

mustard cloth1897

plaster-muslin1899

antiphlogistin1901

1599 A. M. tr. O. Gaebelkhover Bk. Physicke 110/1 We must also have for the same intente, Compressions, or little pillowes of inveterate linnen.

b. Short for ‘compression of the brain’.

ΘΚΠ

the world > health and disease > ill health > a disease > disorders of internal organs > disorders of nervous system > [noun] > disorders of brain > compression

compression1847

1847 J. F. South tr. Chelius Syst. Surg. I. 410 It is often very difficult to distinguish between drunkenness and either concussion or compression.

1870 T. Holmes Syst. Surg. (ed. 2) II. 257 In well-marked compression, however, the patient is generally perfectly insensible.

Compounds

C1. General attributive.

compression bellows n.

ΚΠ

1852 tr. J. J. Seidel Organ & its Constr. 26 Kaufmann, of Dresden..invented the so-called compression-bellows.

compression chamber n.

ΚΠ

1874 E. H. Knight Amer. Mech. Dict. I. 603/1 The compression-chamber receives its successive charges of air from the atmosphere by valves opening inward.

compression gauge n.

ΚΠ

1912 Motor Man. (ed. 14) 234 Each cylinder fails to show a high reading on a compression gauge.

compression machine n.

ΚΠ

1874 E. H. Knight Amer. Mech. Dict. I. 603/1 The power of such a compression machine.

compression spring n.

ΚΠ

1904 A. B. F. Young Compl. Motorist iv. 82 The steering on the car is of an exceedingly strong character... Very strong and stiff compression springs effectually prevent any possibility of ‘backlash’.

compression treatment n.

C2.

compression-casting n. a method of casting bronzes, etc., in which the metal is forced by compression into the finer tracery of the mould.

compression-cock n. a tap having a collapsible india-rubber tube.

compression-ignition engine n. an internal-combustion engine in which the compression of air in the cylinder provides heat to ignite the fuel, as in a Diesel engine.

ΘΚΠ

society > occupation and work > equipment > machine > machines which impart power > engine > internal-combustion engine > [noun] > other types

square motor1912

compression-ignition engine1926

square engine1930

stroker1948

rebore1967

1926 Engineering 27 Aug. 277/2 A compression-ignition engine with its high expansion ratio may be expected to consume a smaller weight of fuel per horse-power than a petrol engine.

1933 Jrnl. Royal Aeronaut. Soc. 37 455 Knock under certain conditions of operation of compression ignition engines may be due to vaporisation of fuel oil during the delay period.

compression-ignition n. this principle or process.

ΘΚΠ

society > occupation and work > equipment > machine > machines which impart power > engine > internal-combustion engine > [noun] > ignition > types of

pre-ignition1898

auto-ignition1901

magneto ignition1902

tube-ignition1903

coil ignition1911

cold starting1930

compression-ignition1936

1936 Economist 2 May 234/1 The diesel, or compression-ignition, engine requires no preliminary heating.

1936 Economist 2 May 234/1 ‘Compression-ignition’, with a smaller space in front of the engine piston, produced an increase in ‘thermal efficiency’.

compression mould n. a mould which encompasses the material to be shaped (see quot. 1951).

ΘΚΠ

society > occupation and work > equipment > equipment for working with other materials > [noun] > with plastics

transfer mould1933

transfer chamber1946

compression mould1951

preformer1952

slush mould1957

plug assist1958

transfer pot1963

1951 Gloss. Terms Plastics (B.S.I.) 35 Compression mould, a mould which requires to be opened to receive the charge and which forms the material to shape on closing.

compression moulding n. a method of moulding plastics by applying pressure; also, the equipment for carrying out this process; a product of this process.

ΘΚΠ

society > occupation and work > industry > working with specific materials > working with rubber or plastic > [noun] > moulding plastics

preforming1931

injection moulding1932

compression moulding1940

transfer moulding1940

slush moulding1943

postforming1945

vacuum forming1946

drape forming1958

thermoforming1958

1940 Chambers's Techn. Dict. 186/1 Compression moulding. The material is placed in a hardened, ground, polished steel container and forced down by means of a plunger at a pressure of 3000–5000 lb. per sq. in.

1958 Spectator 25 July 150/3 It also manufactures signalling equipment, compression moulding, electrical components.

compression ratio n. the ratio of the maximum to the minimum volume in the cylinder of an internal-combustion engine, measured before and after compression (one piston stroke).

ΘΚΠ

society > occupation and work > equipment > machine > machines which impart power > engine > internal-combustion engine > [noun] > piston > movement in > measurement of

compression ratio1907

1907 F. Strickland Man. Petrol Motors & Motor Cars i. iii. 20 The actual compression ratio to be used in an engine is one of the most important points in its design.

1934 Jrnl. Royal Aeronaut. Soc. 38 44 About 13½:1 is more usual with the open combustion chamber, but with the ‘swirl’ type which he had descibed,..the higher compression ratio was possible.

1958 Times 1 July 6/6 It differs from the saloon engine, however, in having a compression ratio of seven to one.

compression rib n. (see quot.).

ΚΠ

1918 E. S. Farrow Dict. Mil. Terms Compression Rib, in an aëroplane, a rib that acts as an ordinary rib, besides bearing the stress of compression produced by the tension of the internal bracing wires.

compression stroke n. the stroke of the piston effecting the compression of the gas and air in the cylinder of an engine.

ΘΚΠ

society > occupation and work > equipment > machine > machines which impart power > engine > internal-combustion engine > [noun] > piston > movement in

compression stroke1894

power stroke1903

1894 B. Donkin Text-bk. Gas, Oil, & Air Engines i. vii. 90 The compression stroke forces this residuum and part of the fresh charge up the narrow passage leading to the hot tube, and causes ignition.

1908 Westm. Gaz. 22 Oct. 4/3 The compression-stroke, in which the piston, by its upward motion compresses the charge of gas into the head of the cylinder.

1912 Motor Man. (ed. 14) 237 The power is developed during a complete cycle of four strokes..one occurring at each half revolution or every stroke of the piston; thus (1) suction stroke, (2) compression stroke [etc.].

compression wood n. a type of wood that develops on the undersides of branches and at the bases of leaning trunks of softwood trees.

ΘΚΠ

the world > plants > part of plant > part of tree or woody plant > wood > [noun] > juvenile or reaction wood

redwood1916

tension wood1924

compression wood1925

reaction wood1948

juvenile wood1956

1925 Spiral Tracheids & Fiber-Tracheids: Tropical Woods (Yale Univ. Sch. of Forestry) 12 In so-called compression wood or ‘red’ wood (rotholz), found in both the Angiospermae and Gymnospermae, the cells have a thick laminated secondary wall, slit into a large number of closely compressed spiral lamellae.

1940 Chambers's Techn. Dict. 186/1 Compression wood.

Draft additions 1997

a. Electronics and Telecommunications. The reduction of the variability of a signal; spec. the introduction of a variable gain factor in such a way as to reduce the range over which the signal amplitude varies.

ΘΚΠ

society > communication > telecommunication > [noun] > signal > reduction of variability of signal

compression1938

digital compression1970

1938 G. E. Sterling Radio Man. (ed. 3) iv. 124 Even weak speech-sounds can be made to over-ride noise..without overloading the transmitter on the sounds which are (before compression) strong.

1943 F. E. Terman Radio Engineers' Handbk. v. 412 Expanders are used to counteract the compression of volume range that is necessary in sound recording.

1986 W. Sinnema Digital, Analog, & Data Communication (ed. 2) iii. 139 Compression is applied to the signal to slightly reduce the maximum signal amplitudes and significantly raise the minimum signal amplitudes.

b. Computing. [translating Russian svertȳvanie; first used in Russian in this sense by L. N. Korolev 1957, in Dokladȳ Akad. Nauk SSSR 113 746.] The process of reducing the amount of space occupied by data that is being stored or transmitted, by minimizing redundant information.

ΘΚΠ

society > computing and information technology > data > [noun] > file > compressing files

compression1957

1957 tr. L. N. Korolev in Doklady Acad. Sci. U.S.S.R. 113 724 (title) Coding and compression of codes.

1966 Datamation Apr. 39/1 Data compression eliminates redundant data and retains useful data.

1987 S. Brand Media Lab i. v. 81 Analogy is a wonderful way to think of semantic data compression: this signal is like that signal, and you got that signal already.

1991 Personal Computer World Feb. 20/2 The MNP level-5 error correction and compression offers up to 80% additional throughput.

This entry has not yet been fully updated (first published 1891; most recently modified version published online December 2021).

单词	compression
释义	compressionn. /kəmˈprɛʃən/ Forms: Also Middle English–1500s comprysion, comprission. Etymology: < French compression, < Latin compressiōn-em , noun of action, < comprimĕre (participial stem compress- ): see compress v. 1. a. The action of compressing; pressing together, squeezing; forcing into a smaller compass; condensation by pressure. ΘΚΠ the world > space > extension in space > reduction in size or extent > [noun] > compression or constriction compressing1398 compressionc1400 constrictionc1400 spanning1527 coarctation1540 restriction1580 choking1635 coarction1782 the world > matter > constitution of matter > density or solidity > [noun] > becoming or making dense or solid > by compaction or compression compaction1398 compressionc1400 constipation1603 compressure1644 compacting1697 the world > matter > physics > mechanics > force > [noun] > pressure > compression compressionc1400 c1400 Lanfranc's Cirurg. (MS. A) 23 A gristil..haþ sixe helpingis [uses]..þo .ij. þat þe harde schulde not hirte þe neische, nameli in þe tyme of compressioun [v.r. comprission], & in þe tyme of smytinge. ?1592 Trag. Solyman & Perseda sig. C3 Why what is iewels, or what is gould but earth, An humor knit together by compression. 1597 P. Lowe Art Chirurg. (1634) 58 Cast forth by the great dilation of the heart or else by the great comprysion thereof. 1659 J. Leak tr. I. de Caus New Inventions Water-works Pref. 3 Water cannot be forced by compression to be contained in less space then its Natural extension. 1774 O. Goldsmith Hist. Earth II. 59 The infant itself has milk in its own breasts, which may be squeezed out by compression. 1863 J. Tyndall Heat (1870) i. §7. 6 To consider the development of heat by compression. b. Constraint, coercion. ΘΚΠ society > authority > subjection > obedience > compulsion > [noun] needeOE distressc1384 force1387 stressc1390 artingc1400 coactionc1400 constrainauncec1400 compulsion1462 enforcement1477 coercion1495 forcement1524 enforcing1531 strain1532 constraint1533 coercement1592 constrainment1593 duress1596 compulse1616 obligement1641 cogency1702 coercive control1827 steamrolling1879 compression1880 1880 Church Times 10 Nov. 779 Dwelling chiefly upon the causes of modern infidelity in France, [he] does not hesitate to ascribe it in a great measure to the compression exercised by Louis XIV. c. figurative. The condensation of thought or language. ΘΚΠ the world > the universe > planet > [noun] > part of planet > polar flattening polar flattening1784 compression1820 society > leisure > the arts > literature > style of language or writing > conciseness > [noun] > compressed quality > compression contraction1655 condensation1798 compression1820 compressure1833 1820 M. R. Mitford in A. G. L'Estrange Life M. R. Mitford (1870) II. v. 92 Great as our merits might be in some points, we none of us excelled in compression. 1850 A. Jameson Legends Monastic Orders Pref. p. xv The difficulty of compression has been the greatest of all my difficulties. d. In a steam-engine, the reduction in volume of the steam left in the cylinder after the exhaust is closed towards the end of the exhaust stroke. ΘΚΠ society > occupation and work > equipment > machine > machines which impart power > engine > steam engine > [noun] > steam > reduction in compression1859 1859 W. J. M. Rankine Man. Steam Engine iii. iii. 420 Compression, or cushioning, is effected by closing the eduction valve before the end of the return stroke. 1871 Eng. Mechanic 7 July 377 The relative ratios of compression and of expansion during the exhaust and steam strokes. 1883 M. N. Forney Catech. Locomotive 44 The steam-port is also closed to the exhaust, or compression, as it is called. 1886 Sci. Amer. 54 56/2 ‘Compression’ [in a steam-engine] is confinement of steam by closing the exhaust opening before the return stroke is ended, thus causing a rise in pressure. 1913 W. R. King Steam Engin. v. 105 This compression provides an elastic cushion of steam which absorbs the momentum of the reciprocating parts of the engine and brings them to rest without shock. 1936 E. A. Phillipson Steam Locomotive Design x. 317 The compression point should advance when the engine is running..at high piston speeds, in order that sufficient cushioning may be available to counteract the greatly augmented inertia forces then set up by the reciprocating masses. e. In an internal-combustion engine, the reduction in volume of the mixture of fuel and air drawn into the cylinder; also, the value or effectiveness of this as a factor affecting the running of the engine. ΘΚΠ society > occupation and work > equipment > machine > machines which impart power > engine > internal-combustion engine > [noun] > fuel or air mixture stratified charge1886 compression1887 stratification1914 swirl1926 secondary air1931 squish1934 1887 D. Clerk Gas Engine (ed. 2) vii. 197 When compression is completed the igniting valve acts and the explosion impels the piston. 1887 Encycl. Brit. XXII. 523/1 Compression did not in his case increase what may be called the theoretical thermodynamic efficiency. 1907 R. B. Whitman Motor-car Princ. xi. 193 Other losses of compression may be due to a cracked piston. 1908 Westm. Gaz. 20 Aug. 4/2 It has been aptly stated that the carburetter is the lungs of the internal-combustion engine, and in a similar way the compression may be said to represent the muscle. 1912 Motor Man. (ed. 14) 227 No engine ever pulled well with feeble compression. 1963 D. V. W. Francis Morris Engines i. 7 It should be possible to feel a good and even compression for all the cylinders. f. The process of subjecting to compressed air in an air-lock. ΚΠ 1906 Westm. Gaz. 27 Jan. 10/1 The men who controlled the airlocks, and were subjected to compression and decompression every few minutes, were in no case affected. 2. a. A state or condition of being compressed. ΘΚΠ the world > space > extension in space > reduction in size or extent > [noun] > compression or constriction > state or condition compression1603 astringency1669 comprehension1712 1603 J. Florio tr. M. de Montaigne Ess. i. xx. 43 Those instruments..have their proper compressions and dilatations, [etc.]. 1771 H. Mackenzie Man of Feeling (1886) 37 His fingers lost their compression. 1849 R. I. Murchison Siluria ix. 204 Every variety of distortion and compression. 1871 J. Tyndall Fragm. Sci. (ed. 6) I. ix. 300 The moraine is in a state of longitudinal compression. b. of thought, language, or writing. ΘΚΠ society > leisure > the arts > literature > style of language or writing > conciseness > [noun] > compressed quality compression1759 tabloidization1926 1759 S. Johnson Idler 18 Aug. 257 Best pleased with involution of argument and compression of thought. 1823 J. Badcock Domest. Amusem. p. vi The state of compression in which it [the treatise] now appears. c. figurative. Straitened or repressed condition, under the operation of trouble, tyranny, or the like. ΘΚΠ the world > action or operation > adversity > [noun] > oppression, persecution, or affliction threat971 constraintc1374 oppressiona1382 pressurec1384 aggrievancea1400 thronga1400 oppress1488 aggrievement1646 compression1759 society > authority > subjection > [noun] > to oppressive rule yokeeOE nitheringeOE underputtingc1440 servitude?1473 compression1816 downtroddenness1868 1759 J. Mills tr. H. L. Duhamel du Monceau Pract. Treat. Husbandry ii. ii. 194 The state of compression which those in the common way were in after harvest. 1816 T. Jefferson Writings (1830) IV. 280 That nation is too high-minded..to remain quiet under its present compression. 1879 F. W. Farrar Life & Work St. Paul II. ix. xxxiii. 101 That previous letter..had been written in much tribulation and compression of heart. 3. compression of the poles: the flattening of a planet at the poles, making it an oblate spheroid. ΚΠ 1814 J. Playfair Outl. Nat. Philos. II. i. ix. 179 The compression of Jupiter amounts to a fourteenth part of his longer diameter. 1849 M. Somerville On Connexion Physical Sci. (ed. 8) iv. 34 Of ascertaining the compression of Jupiter's spheroid. †4. Surgery. a. A compress. Obsolete. rare. ΘΚΠ the world > health and disease > healing > medical appliances or equipment > equipment for treating wound or ulcer > [noun] > poultice, plaster, or compress plasterOE clydec1325 emplastera1382 entretea1400 pottagea1400 poulticea1400 faldellac1400 treatc1400 Gratia Dei?a1425 magdaleon?a1425 strictorya1425 grace of Godc1450 emplastrum?1541 malagma?1541 sparadrap1543 spasmadrap?a1547 plasture?1550 mustard plaster1562 cataplasm1563 oint-plaster1578 quilt1583 compress1599 compression1599 diachylum-plaster1599 pulment1599 pulvinar1599 frontlet1600 sinapism1601 epithemation1615 diapalma1646 opodeldoc1646 attraction1656 treacle plaster1659 melilot emplaster1676 stay1676 oxycroceum1696 melilot plaster1712 adhesive1753 bag1753 mustard poultice1765 soap plaster1789 water dressing1830 poor man's plaster1833 compressor1851 spongiopiline1851 vinegar-poultice1854 water-strapping1854 pitch-plaster1858 jacket poultice1862 mustard leaf1869 mustard paper1874 piline1874 plaster-mull1890 mustard cloth1897 plaster-muslin1899 antiphlogistin1901 1599 A. M. tr. O. Gaebelkhover Bk. Physicke 110/1 We must also have for the same intente, Compressions, or little pillowes of inveterate linnen. b. Short for ‘compression of the brain’. ΘΚΠ the world > health and disease > ill health > a disease > disorders of internal organs > disorders of nervous system > [noun] > disorders of brain > compression compression1847 1847 J. F. South tr. Chelius Syst. Surg. I. 410 It is often very difficult to distinguish between drunkenness and either concussion or compression. 1870 T. Holmes Syst. Surg. (ed. 2) II. 257 In well-marked compression, however, the patient is generally perfectly insensible. Compounds C1. General attributive. compression bellows n. ΚΠ 1852 tr. J. J. Seidel Organ & its Constr. 26 Kaufmann, of Dresden..invented the so-called compression-bellows. compression chamber n. ΚΠ 1874 E. H. Knight Amer. Mech. Dict. I. 603/1 The compression-chamber receives its successive charges of air from the atmosphere by valves opening inward. compression gauge n. ΚΠ 1912 Motor Man. (ed. 14) 234 Each cylinder fails to show a high reading on a compression gauge. compression machine n. ΚΠ 1874 E. H. Knight Amer. Mech. Dict. I. 603/1 The power of such a compression machine. compression spring n. ΚΠ 1904 A. B. F. Young Compl. Motorist iv. 82 The steering on the car is of an exceedingly strong character... Very strong and stiff compression springs effectually prevent any possibility of ‘backlash’. compression treatment n. C2. compression-casting n. a method of casting bronzes, etc., in which the metal is forced by compression into the finer tracery of the mould. compression-cock n. a tap having a collapsible india-rubber tube. compression-ignition engine n. an internal-combustion engine in which the compression of air in the cylinder provides heat to ignite the fuel, as in a Diesel engine. ΘΚΠ society > occupation and work > equipment > machine > machines which impart power > engine > internal-combustion engine > [noun] > other types square motor1912 compression-ignition engine1926 square engine1930 stroker1948 rebore1967 1926 Engineering 27 Aug. 277/2 A compression-ignition engine with its high expansion ratio may be expected to consume a smaller weight of fuel per horse-power than a petrol engine. 1933 Jrnl. Royal Aeronaut. Soc. 37 455 Knock under certain conditions of operation of compression ignition engines may be due to vaporisation of fuel oil during the delay period. compression-ignition n. this principle or process. ΘΚΠ society > occupation and work > equipment > machine > machines which impart power > engine > internal-combustion engine > [noun] > ignition > types of pre-ignition1898 auto-ignition1901 magneto ignition1902 tube-ignition1903 coil ignition1911 cold starting1930 compression-ignition1936 1936 Economist 2 May 234/1 The diesel, or compression-ignition, engine requires no preliminary heating. 1936 Economist 2 May 234/1 ‘Compression-ignition’, with a smaller space in front of the engine piston, produced an increase in ‘thermal efficiency’. compression mould n. a mould which encompasses the material to be shaped (see quot. 1951). ΘΚΠ society > occupation and work > equipment > equipment for working with other materials > [noun] > with plastics transfer mould1933 transfer chamber1946 compression mould1951 preformer1952 slush mould1957 plug assist1958 transfer pot1963 1951 Gloss. Terms Plastics (B.S.I.) 35 Compression mould, a mould which requires to be opened to receive the charge and which forms the material to shape on closing. compression moulding n. a method of moulding plastics by applying pressure; also, the equipment for carrying out this process; a product of this process. ΘΚΠ society > occupation and work > industry > working with specific materials > working with rubber or plastic > [noun] > moulding plastics preforming1931 injection moulding1932 compression moulding1940 transfer moulding1940 slush moulding1943 postforming1945 vacuum forming1946 drape forming1958 thermoforming1958 1940 Chambers's Techn. Dict. 186/1 Compression moulding. The material is placed in a hardened, ground, polished steel container and forced down by means of a plunger at a pressure of 3000–5000 lb. per sq. in. 1958 Spectator 25 July 150/3 It also manufactures signalling equipment, compression moulding, electrical components. compression ratio n. the ratio of the maximum to the minimum volume in the cylinder of an internal-combustion engine, measured before and after compression (one piston stroke). ΘΚΠ society > occupation and work > equipment > machine > machines which impart power > engine > internal-combustion engine > [noun] > piston > movement in > measurement of compression ratio1907 1907 F. Strickland Man. Petrol Motors & Motor Cars i. iii. 20 The actual compression ratio to be used in an engine is one of the most important points in its design. 1934 Jrnl. Royal Aeronaut. Soc. 38 44 About 13½:1 is more usual with the open combustion chamber, but with the ‘swirl’ type which he had descibed,..the higher compression ratio was possible. 1958 Times 1 July 6/6 It differs from the saloon engine, however, in having a compression ratio of seven to one. compression rib n. (see quot.). ΚΠ 1918 E. S. Farrow Dict. Mil. Terms Compression Rib, in an aëroplane, a rib that acts as an ordinary rib, besides bearing the stress of compression produced by the tension of the internal bracing wires. compression stroke n. the stroke of the piston effecting the compression of the gas and air in the cylinder of an engine. ΘΚΠ society > occupation and work > equipment > machine > machines which impart power > engine > internal-combustion engine > [noun] > piston > movement in compression stroke1894 power stroke1903 1894 B. Donkin Text-bk. Gas, Oil, & Air Engines i. vii. 90 The compression stroke forces this residuum and part of the fresh charge up the narrow passage leading to the hot tube, and causes ignition. 1908 Westm. Gaz. 22 Oct. 4/3 The compression-stroke, in which the piston, by its upward motion compresses the charge of gas into the head of the cylinder. 1912 Motor Man. (ed. 14) 237 The power is developed during a complete cycle of four strokes..one occurring at each half revolution or every stroke of the piston; thus (1) suction stroke, (2) compression stroke [etc.]. compression wood n. a type of wood that develops on the undersides of branches and at the bases of leaning trunks of softwood trees. ΘΚΠ the world > plants > part of plant > part of tree or woody plant > wood > [noun] > juvenile or reaction wood redwood1916 tension wood1924 compression wood1925 reaction wood1948 juvenile wood1956 1925 Spiral Tracheids & Fiber-Tracheids: Tropical Woods (Yale Univ. Sch. of Forestry) 12 In so-called compression wood or ‘red’ wood (rotholz), found in both the Angiospermae and Gymnospermae, the cells have a thick laminated secondary wall, slit into a large number of closely compressed spiral lamellae. 1940 Chambers's Techn. Dict. 186/1 Compression wood. Draft additions 1997 a. Electronics and Telecommunications. The reduction of the variability of a signal; spec. the introduction of a variable gain factor in such a way as to reduce the range over which the signal amplitude varies. ΘΚΠ society > communication > telecommunication > [noun] > signal > reduction of variability of signal compression1938 digital compression1970 1938 G. E. Sterling Radio Man. (ed. 3) iv. 124 Even weak speech-sounds can be made to over-ride noise..without overloading the transmitter on the sounds which are (before compression) strong. 1943 F. E. Terman Radio Engineers' Handbk. v. 412 Expanders are used to counteract the compression of volume range that is necessary in sound recording. 1986 W. Sinnema Digital, Analog, & Data Communication (ed. 2) iii. 139 Compression is applied to the signal to slightly reduce the maximum signal amplitudes and significantly raise the minimum signal amplitudes. b. Computing. [translating Russian svertȳvanie; first used in Russian in this sense by L. N. Korolev 1957, in Dokladȳ Akad. Nauk SSSR 113 746.] The process of reducing the amount of space occupied by data that is being stored or transmitted, by minimizing redundant information. ΘΚΠ society > computing and information technology > data > [noun] > file > compressing files compression1957 1957 tr. L. N. Korolev in Doklady Acad. Sci. U.S.S.R. 113 724 (title) Coding and compression of codes. 1966 Datamation Apr. 39/1 Data compression eliminates redundant data and retains useful data. 1987 S. Brand Media Lab i. v. 81 Analogy is a wonderful way to think of semantic data compression: this signal is like that signal, and you got that signal already. 1991 Personal Computer World Feb. 20/2 The MNP level-5 error correction and compression offers up to 80% additional throughput. This entry has not yet been fully updated (first published 1891; most recently modified version published online December 2021). < n.c1400
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