| 释义 |
▪ I. threshold, n.|ˈθrɛʃəʊld, ˈθrɛʃhəʊld|
Forms: see below.
[OE. þerscold, -wold, þerxold, -wold, þrexold, -wold = ON. þreskjǫldr, -kǫldr, nom. pl. þreskeldir, mod.Icel. þröskuldr, Norw., Sw. tröskel, Da. (dør)tærskel; cf. OHG. driscûfli neuter, MHG. drischuvel, durschufel, Ger. dial. drischaufel, etc. The first element is generally identified with thresh v. (? in its original sense ‘to tread, trample’), the forms of which it generally follows; but the second is doubtful, and has in English, as in other langs., undergone many popular transformations.]
1. a. The piece of timber or stone which lies below the bottom of a door, and has to be crossed in entering a house; the sill of a doorway; hence, the entrance to a house or building.
(α) 1 þresc-, þrex-, þerxold, 5 thresshhold, 6 threshould, thressald, threszsh-, tresholde, 6–7 thresholde, 6– threshold.
c1000ælfric Exod. xii. 22 And dippað ysopan sceaft on þam blode, þe ys on þam þerxolde. ― Deut. vi. 9 And write þa on þinum þrescolde. c1000Ðrexold [see β]. 1513Douglas æneis vi. i. 100 To the dur thressald cumin ar thai. 1530Palsgr. 280/2 Thresholde, seuil de luys [l'uis]. 1535Coverdale 1 Sam. v. 5 They..treade not vpon the threszsholde of Dagon. ― Prov. xxvi. 14 Like as the dore turneth aboute vpon the tresholde. 1553Becon Reliques of Rome (1563) 256 b, At euery time the bishop shal come vnto y⊇ church dore & strike y⊇ threshold thereof with his Crossier staffe. 1607Shakes. Cor. iv. v. 124. 1727 Gay Fables xxiii. 30 The horse-shoe's nail'd (each threshold's guard). 1837Lytton E. Maltrav. i. i, A tall figure crossed the threshold.
(β) 1 þrex-, þræx-, þreox, ðærsc-, þersc-, þeorsc-, þercs-, þer(e)xwold, þrexwald, -weald, þersc-, þærsc-, þirscwald, 2 þreoxwold, 4 þrex-, thresshe-, thresh-, threswold, thers-, þreis-, thrys-, throssche-, treswald, 5 thrys-, threschwolde, thris-, thresche-, thryshwald, 6 threskwolde (9 dial. thresh-wood).
[c888Þeorscwold: see sense 2.] 971Blickl. Hom. 207 Of ðæs portices dura..ðærscwolde wæs ᵹesyne þæt [etc.]. c1000ælfric Gram. ix. (Z.) 40 Limen, ofersleᵹe oððe þerexwold [v.rr. þræx-, þreox-, þerxwold, ðrexold]. c1000Sax. Leechd. II. 142 Ofer þa duru, & under þone þerxwold. c1000Ags. Voc. in Wr.-Wülcker 280/15 Limen, þerscwald. 11..Voc. ibid. 551/32 Limen, ofersleie, uel þreoxwold. c1325Gloss. W. de Bibbesw. in Wright Voc. 170 La lyme, the therswald. 1362Langl. P. Pl. A. v. 201 He þrompelde atte þrexwolde [v.rr. þresshewold, þreschfold, throschfold] and þreuh to þe grounde. c1375Sc. Leg. Saints xviii. (Egipciane) 579 Quhen we come to þe thryswald. Ibid. 593, I..furth can gange to þe treswald. 1382Wyclif 1 Kings xiv. 17 Whanne she wente in the threshwold of the hows, the child dyede. c1386Chaucer Clerk's T. 232 (Lansd.) And as sche wolde ouer þe þresshewolde gon [Camb. throswald, Petw. thresshold, Ellesm., Heng., Corp. thresshfold, Harl. þreisshfold]. c1400Ywaine & Gaw. 3222 He come to the thriswald. 14..Nom. in Wr.-Wülcker 733/8 Hoc limen, -nis, thryswold. c1440Promp. Parv. 492/2 Threschwolde, limen. 1444in J. R. Boyle Hedon (1875) App. 184 Thryshwald. 1483Cath. Angl. 385/1 A Threschewalde, limen. 1511Nottingham Rec. III. 333 Makyng ye seid doore and leyeng of ij. threskwoldes. 1825J. Briggs Rem. 215 (E.D.D.) Upon this thresh-wood..cross straws were laid.
(γ) 4 þreschefolde, threshfoold, þreshe-, thressh-, þresch-, threissh-, threis-, throschfold, 5 thresh-, thresfold(e (9 dial. thresh-fod).
c1374Chaucer Boeth. i. pr. i. 3 (Camb. MS.) They passeden sorwfully the thresshfold [B.M. MS. þreschefolde]. 1382Wyclif Ezek. ix. 3 At the threshfoold [1388 threisfold] of the house. 1393Langl. P. Pl. C. vii. 408 He thrumbled at þe þreshefold [v.rr. þresshfold, þrescwolde, treshfold]. 1413Pilgr. Sowle (Caxton 1483) iii. ix. 56 Not by the dore but vnder the threshfold drawen oute. 14..Voc. in Wr.-Wülcker 592/47 Limen, a thresfolde. 1828Craven Gloss., Thresh-fod, threshold.
(δ) 6 thressholl, 7–8 threshal, 9 dial. threshel, thrashel (drashel).
1593Thressholl [see 2 b]. 1607Chapman Bussy d'Ambois iv. G ij b, Ile make th' inspired threshals of his Court Sweat with the weather of my horrid steps Before I enter. c1645Howell Lett. (1688) IV. 494 He dragg'd her Body to the Threshal of the Door. 1787in Coll. Sc. Poems 12 (E.D.D.) Luckie out o'er the threshal goes. 1898J. Macmanus Bend of Road 90 The house crammed..from the threshel to the backstone. 1900G. Williams Fairmner's Tint Laddies iv. (E.D.D.), To cross the thrashel o' oor hoose.
(ε) dial. 7 treshwart, 9 threshwort, threshut; 9 freshwood: cf. th-1 (6).
1608Vestry Bks. (Surtees) 151 Pd to John Lamb for mendinge of the treshwart of the portch, iiij d. 18..Brierley Out of Work x. (E.D.D.), Mind thou doesno' tumble o'er that threshut. 1888W. Dickinson Lit. Rem. 234 (E.D.D.) The threshwort's worn quite hollow down. 1825J. Briggs Rem. 201 (E.D.D.) The entrance from the front door was called the freshwood. 1879Simmons Lay Folks Mass Bk. Notes 399, I bids thee..never again set thy foot over my freshwood. 1892Heslop Northumbld. Gloss., Fresh-wood, the threshold, or foot-beam of the front door.
¶b. (erron.) The upper horizontal part of a door-case; the lintel. rare.
[Cf.c1000in 1 α, 1 β 1382: see overthreshold.] 1821Clare Vill. Minstr. I. 11 The rural sports of May, When each cot-threshold mounts its hailing bough. 1834H. Martineau Demerara iv. 52 Cassius stood, leaning his forehead against his low threshold.
2. transf. and fig.
a. Border, limit (of a region); the line which one crosses in entering. spec. in an airfield: the beginning of the landing area on a runway. Also attrib.
c888K. ælfred Boeth. xxi, Se ilca [sc. Godes miht] forwyrnð þæræ sæ þæt heo ne mot þone þeorscwold oferstæppan þære eorþan. a900tr. Bæda's Hist. v. vi. (1890) 398 Forðon þe he mæc..from deaðes þirscwalde wæs aceᵹende. 1642Fuller Holy & Prof. St. iii. iv. 159 Know most of the rooms of thy native countrey before thou goest over the threshold thereof. a1863Faber Hymn, ‘The happy Gate of Heaven’ ii, Fair are the thresholds of blue sea. 1899Westm. Gaz. 2 Sept. 2/1 On what is known as ‘the threshold of England’, the Sussex coast. 1937Jrnl. R. Aeronaut. Soc. XLI. 295 Sites..for threshold lighting and other signal apparatus required to assist the pilot. 1960Guide Civil Land Aerodrome Lighting (B.S.I.) 15 A pilot needs to be given a clear indication of the runway threshold and the addition of wingbars, composed of green lights, is recommended to make the threshold more conspicuous in poor visibility.
b. In reference to entrance, the beginning of a state or action, outset, opening. (In quot. 1659, in reference to going out or leaving, close, end.)
c1586C'tess Pembroke Ps. (1823) cxix. R. i, Right wonderfull thy testimonies be,..Their very threshold gives men light. 1593Queen Elizabeth Boeth. ii. pr. iv. 28 The thressholl of thy felicitie. 1659Clarke Papers (Camden) IV. 297, I..shall be moste glad to heare that you are gott over the thresholde of your present troublesome stay in London, the country being the most proper place for [etc.]. 1834L. Ritchie Wand. by Seine 8 The youth, stepping proudly upon the threshold of manhood. 1877Foster Phys. iii. i. (1878) 389 We are..met on the very threshold of every enquiry [etc.].
c. In technical language, a lower limit. (i) Psychol.: esp. in phr. threshold of consciousness: see quots., and cf. limen, subliminal. In Physiol. and more widely: the limit below which a stimulus is not perceptible; the magnitude or intensity of a stimulus which has to be exceeded for it to produce a certain response. (ii) The magnitude or intensity that must be exceeded for a certain reaction or phenomenon to occur.
1874Sully Sensation & Intuition 47 There is a certain limit below which our several sensibilities are unable to discriminate. This boundary..Fechner calls the ‘threshold’ (die Schwelle). 1886Gurney, etc. Phantasms of Living I. 453 A telepathic disturbance may take place below the threshold of consciousness. 1886Ward in Encycl. Brit. XX. 47/2 We do not distinguish or attend separately to presentations of less than a certain assignable intensity. On attaining this intensity presentations are said to pass over the threshold of consciousness, to use Herbart's now classic phrase [‘Schwelle des Bewusstseins’ (Psychol. als Wissenschaft (1824) §47)]. 1902J. M. Baldwin Dict. Philos. & Psychol. II. 696/2 The least noticeable difference in sensation is called the threshold of discrimination or difference. 1919W. D. Halliburton Handbk. Physiol. (ed. 14) lii. 767 That strength of stimulus which just suffices to evoke a sensation is called..its absolute threshold. 1922Electr. Communication I. i. 45/1 Articulation tests were made upon the..telephone system..when it was set to deliver various intensities from the threshold of audibility to very large values. 1930City Noise (N.Y. Noise Abatement Commission) 34 This means decibels above the threshold of hearing. 1931Brit. Jrnl. Psychol. Jan. 285 There is a definite ‘colourless interval’ between the ‘general threshold’, or the intensity which just suffices to produce a sensation of light, and the ‘specific threshold’, or the intensity at which colour is just noticeable. 1936G. K. Zipf Psycho-Biol. of Lang. 113 Every phoneme must also have a lower threshold below which it cannot pass without strengthening. 1938Ann. Reg. 1937 346 The view [was] advanced that spontaneous mutations are mono-molecular reactions produced by thermal agitation when this over⁓steps the energy threshold of the chemical bonds. 1941in M. Gowing Britain & Atomic Energy 1939–1945 (1964) 403 From..the fact that [uranium] 238 does not give fission with slow neutrons, it is clear that the jump at 1 MeV represents the threshold of 238. The fission which takes place with neutrons of energy less than 1 MeV must therefore be ascribed to 235. 1948P. M. Morse Vibration & Sound (ed. 2) vi. 227 The upper contour is the threshold of pain, above which the sensation is more of pain than of sound (and the result is more or less damaging to the ear). 1949Koestler Insight & Outlook xv. 207 Heightening the threshold of some sensory receptors and lowering the threshold of others. 1949S. C. Rothmann Constructive Uses Atomic Energy 205 The Geiger threshold of a radiation counter tube is the lowest operating voltage at which the charge transferred per isolated count is substantially independent of the nature of the initial ionizing event. 1950Gloss. Aeronaut. Terms (B.S.I.) i. 25 Cruising threshold, the equivalent air speed giving the lowest comfortable continuous cruising speed. 1955J. A. Wheeler in W. Pauli Niels Bohr 166 A photofission threshold of 5·15 MeV..goes with a half life against spontaneous fission of the order of 1015·8 years. 1958Oxford Univ. Gaz. 27 Jan. 524/2 (heading) Non-random sequences in visual threshold experiments. 1959Sunday Times 5 July 8/6 The absence of a lower threshold for the production of mutations by radiation. 1962A. Nisbett Technique Sound Studio v. 98 At 1,000 c/s the threshold of pain is 110 dB or more above the threshold of hearing. 1963B. Fozard Instrumentation Nucl. Reactors v. 46 The scaling circuit which is used to count the pulses from the G.M. tube has some more or less well defined ‘threshold’, i.e. it accepts only those pulses which exceed a certain amplitude. 1965Proc. R. Soc. B. CLXI. 338 While a climatic change in one area may have produced conditions very favourable for a new species, in another area the same climatic change may have produced conditions only just above the critical physiological thresholds for the existence of that species. 1965W. Lamb Posture & Gesture iii. 44 There has been a lot of investigation of the threshold of fatigue in athletics and the type of training required to push this threshold back is well understood. 1972J. Mosedale Football ix. 124 Performances like Nevers' demonstrates [sic] the high threshold of pain common to many athletes. 1973Times 19 Oct. 7/8 A GP who might only see one case of child abuse a year might not have as low a threshold of suspicion as I have. 1983Sci. Amer. Jan. 98/2 Above a certain threshold, known as the critical density, the expansion [of the universe] will eventually cease and contraction will begin.
(iii) In contexts of wages and taxation, in which wage or tax increases become due or obligatory when some predetermined conditions are fulfilled (esp. above a specified point on a graduated scale). Also in more general use in contexts of work. Freq. attrib.
1967L. B. Archer in Wills & Yearsley Handbk. Managem. Technol. 131 Usually there is a threshold between ‘good enough’ and ‘not good enough’ in respect of each objective, below which a design proposal would not be acceptable. 1971Guardian 7 Sept. 11/2 Mr [Tom] Jackson..argued in favour of a single threshold claim on behalf of all public employees. 1972Observer 13 Aug. 10/8 Threshold cost of living agreements could make things much happier so long as the threshold is put fairly high and/or there is a big reduction in the effective basic level of wage settlements. 1974Ann. Reg. 1973 14 The main features of the incomes plan [of Mr. Edward Heath] were..threshold payments of a maximum of 40p. a week if the retail price index were to rise by 7 per cent [etc.]. 1976[see tax threshold s.v. tax n.1 7 b]. 1979H. Wilson Final Term ii. 42 Viewed with hindsight the thresholds were a disastrous mistake. That does not in fact mean that Mr Heath had been wrong to introduce them in October 1973. 1980J. Boyd-Carpenter Way of Life xiii. 169 The alternative relief was to make a big increase in the level of the ‘Thresholds’, that is to say the point on the income scale at which people became liable to tax.
†d. An obstacle, stumbling-block. Obs.
1601Sir W. Cornwallis Ess. iv, Makes his imagination build blockes and thresholds, in the plainest and most beaten way. 1705Hickeringill Priest-cr. ii. vii. 70, I hope it was left by chance, and not on purpose to be a Threshold, or Stumbling-block at the Church Door. Ibid. viii. 91.
3. attrib. and Comb.
a.
1535Coverdale 2 Kings xxii. 5 The money that is brought vnto y⊇ house of y⊇ Lorde (which the tresholde kepers haue gathered). a1661B. Holyday Juvenal vi. (1673) 95 The hangings too, and threshold-boughs yet green. 1678Otway Friendship in F. v. i, Let all the Doors be barr'd.., and Gunpowder under each Threshold-place. 1805Scott Last Minstr. i. i, No living wight, save the Ladye alone, Had dared to cross the threshold stone. 1842Tennyson St. Sim. Styl. 188 His footsteps smite the threshold stairs Of life.
b. (Having a value or intensity) equal to that of a threshold (sense 2 c).
1906J. R. Murlin tr. Tigerstedt's Text-bk. Human Physiol. xvi. 455 In order that an external stimulus may produce a sensation, it must exceed a certain lower limit of strength, which is called, after Herbart, the threshold value of the stimulus. 1921J. Mills Within Atom 215 Threshold frequency, the minimum frequency of radiation which will produce photo-electric effects. 1926J. S. Huxley Ess. Pop. Sci. 199 It is needful, not merely that some thyroid secretion should be circulating in the body, but that it should reach a certain definite concentration, a certain ‘threshold value’. 1941in M. Gowing Britain & Atomic Energy 1939–45 (1964) 400 Neutrons of less than a certain threshold energy..do not cause fission of 238U. 1959Listener 26 Nov. 929/1 It is possible that the radiation level has to exceed a critical or threshold value before any genetical effects arise. 1964W. G. Smith Allergy & Tissue Metabolism ii. 23 The tissue response would depend upon the number of susceptible cells..reached by a threshold concentration of histamine. 1971J. H. Smith Digital Logic iv. 69 The device is actuated when the input signal crosses a certain ‘threshold’ voltage. 1978J. Paxton Dict. European Econ. Community (rev. ed.) 46 Imports were kept up to minimum, or threshold, prices by means of variable import levies.
c. Electronics. threshold device, threshold element, etc.: a circuit element having one output and a number of inputs, each of which accepts a binary signal and multiplies it by some factor; the output is 0 or 1 depending on whether or not the sum of the resulting quantities is less than a certain threshold value; threshold function, a Boolean function that can be realized by such an element; threshold logic, threshold switching (based on such elements).
1960IRE Trans. Electronic Computers IX. 122/1 Another useful logical two-state device is a threshold element. 1960Proc. IRE XLVIII. 1335/3 The increasing use of threshold devices such as magnetic cores and parametrons. 1961IRE Trans. Electronic Computers X. 6/1 Linearly separable switching functions..have been studied under different names, such as..linear-input logic, threshold logic, majority logic, and voting logic. Ibid. 798/2 Elementary threshold functions, i.e., functions that can be implemented by a single threshold circuit, are first characterized for the cases of 2, 3, and 4 variables. 1962Proc. Internat. Federation Information Processing Congr. 757/1 A threshold gate determines its output in two steps: a linear summation followed by a discrimination. 1964H. C. Torng Introd. Logical Design of Switching Systems viii. 133 Threshold switching devices are..extensively used in pattern recognition systems and perception-like automata. 1970Z. Kohavi Switching & Finite Automata Theory vii. 183 One of the limitations of threshold logic is its sensitivity to variations in circuit parameters. 1975N. N. Biswas Introd. Logic & Switching Theory vii. 183 In many cases where the nand or nor realizations may require a number of gates, the threshold logic may realize the function by only one gate. 1978S. C. Lee Mod. Switching Theory iv. 117 As another simple example of a threshold function, consider f(x1, x2, x3) = x1x2 + x3.
▪ II. threshold, v.|ˈθrɛʃhəʊld|
[f. the n.]
trans. To alter (an image) by reproducing it in two tones only, each part being dark or light according as the original is darker or lighter than some chosen threshold shade. Hence ˈthresholding vbl. n.
1968Brit. Med. Bull. XXIV. 262/2 One..comes across objects which have obviously been thresholded at too low or too high a level, resulting in incorrect segmentation. Ibid., Simple thresholding (setting a limit above which everything is considered to be picture and below which everything is considered to be background) seems to work out quite well in coarse density-resolution scanners. 1976Physics Bull. Sept. 381/3 Figure 2 shows the result of magnifying and electronically thresholding a small portion of a landsat infrared image of the UK. 1983What's New in Computing Jan. 16/2 The software modules comprise such algorithms as image thresholding, edge enhancement, [etc.]. |