cycloidn.adj.

Brit.

/ˈsʌɪklɔɪd/,

/ˈsɪklɔɪd/, U.S.

/ˈsaɪˌklɔɪd/

Etymology: See cycloid adj.

1. Mathematics.

a. The curve traced in space by a point in the circumference (or on a radius) of a circle as the circle rolls along a straight line.The common cycloid is that traced by a point in the circumference of the circle, and has cusps where this point meets the straight line; that traced by a point within the circle is a prolate cycloid (with inflections); by a point without the circle, a curtate cycloid (with loops).

ΘΚΠ

the world > relative properties > number > geometry > curve > [noun] > generated by or related to a point > by revolution

cycloid1661

epicycloid1696

trochoid1704

involute figure or curve1706

roulette1708

evolute1753

epicycle1756

involute1796

hypocycloid1843

hypotrochoid1843

axoid1876

epicyclic1878

astroid1886

1661 R. Boyle New Exper. Physico-mech. (1682) 101 Each point will by this compound motion describe on the plain..a perfect cycloid.

1726 J. Swift Gulliver II. iii. ii. 20 A Pudding [cut] into a Cycloid.

1812 J. Playfair Outl. Nat. Philos. I. 128 The line in which a heavy body descends in the least time from one given point to another..is an arch of a cycloid... Hence the cycloid is called the line of swiftest descent.

b. companion to the cycloid: the curve formed by successive positions of the point of intersection of a horizontal line drawn through a fixed point in the circumference of the rolling circle with a vertical line through its point of contact with the (horizontal) line on which it rolls.

ΚΠ

1837 W. Whewell Hist. Inductive Sci. II. viii. ii. 307 The curve might be of the nature of that which is called the companion to the cycloid.

2. Zoology. A cycloid fish: see cycloid adj.

ΘΚΠ

the world > animals > fish > parts of fish > [noun] > scales or parts of > fish having > fish having circular scales or cycloid

cycloidean1836

cycloid1847

1847 D. T. Ansted Anc. World x. 246 Two orders of Fishes..the Ctenoids and Cycloids.

3. Psychiatry. A person characterized by a tendency to alternate between exhilaration and depression. Also attributive or as adj.

ΘΚΠ

the world > health and disease > mental health > mental illness > degree or type of mental illness > [noun] > mania > manic depression > person

manic-depressive1902

cycloid1925

cyclothyme1925

cyclothymic1925

the world > health and disease > mental health > mental illness > degree or type of mental illness > [adjective] > affected with mania > specifically in psychiatry > manic-depressive > liable to manic depression

cycloid1925

cyclothyme1925

cyclothymic1925

syntonic1925

1925 W. J. H. Sprott tr. E. Kretschmer Physique & Char. xi. 127 In an adverse situation the cycloid is either sorrowful or hot-headed, but he is never in the very least nervous.

1927 D. K. Henderson & R. D. Gillespie Text-bk. Psychiatry ix. 190 The ‘syntonic’ or ‘cycloid’ personality, in which, if mental illness develops, it tends to be of the manic-depressive kind.

1929 F. H. Garrison Introd. Hist. Med. (ed. 4) 679 Cycloids are cheerful, temperamental, well adjusted to the business world, but liable to sudden alternations of exhilaration and depression.

1943 H. Read Educ. through Art iv. 76 The ‘depressive cycloid’ temperament is certainly our old friend the melancholic humour.

This entry has not yet been fully updated (first published 1893; most recently modified version published online March 2022).

cycloidadj.

Etymology: < Greek κυκλοειδής, κυκλώδης circular: see cycle n.¹ and -oid suffix.Previous versions of the OED give the stress as: ˈcycloid.

Resembling a circle; spec. in Zoology (a) of a somewhat circular form, with concentric striations; applied to the scales of certain fishes; (b) belonging to the Cycloidei, or order of fishes with cycloid scales.

ΘΚΠ

the world > animals > fish > parts of fish > [adjective] > having scales > of specific type

lepidoid1836

cycloid1847

ganoid1847

ctenoid1851

the world > animals > fish > parts of fish > [adjective] > having scales > of scales of specific type

fulcral1809

placoid1842

cycloid1847

ctenoid1872

cycloidal1872

1847 D. T. Ansted Anc. World iv. 62 The remaining two groups [of Fishes] are called respectively Ctenoid..and Cycloid..from the shape and structure of the scale.

1851 G. F. Richardson Introd. Geol. (1855) 283 Nearly all the cycloid genera..are extinct.

1872 H. A. Nicholson Man. Palæontol. 326 Scales cycloid or rhomboid.

This entry has not yet been fully updated (first published 1893; most recently modified version published online June 2019).

单词	cycloid
释义	cycloidn.adj. Brit. /ˈsʌɪklɔɪd/, /ˈsɪklɔɪd/, U.S. /ˈsaɪˌklɔɪd/ Etymology: See cycloid adj. 1. Mathematics. a. The curve traced in space by a point in the circumference (or on a radius) of a circle as the circle rolls along a straight line.The common cycloid is that traced by a point in the circumference of the circle, and has cusps where this point meets the straight line; that traced by a point within the circle is a prolate cycloid (with inflections); by a point without the circle, a curtate cycloid (with loops). ΘΚΠ the world > relative properties > number > geometry > curve > [noun] > generated by or related to a point > by revolution cycloid1661 epicycloid1696 trochoid1704 involute figure or curve1706 roulette1708 evolute1753 epicycle1756 involute1796 hypocycloid1843 hypotrochoid1843 axoid1876 epicyclic1878 astroid1886 1661 R. Boyle New Exper. Physico-mech. (1682) 101 Each point will by this compound motion describe on the plain..a perfect cycloid. 1726 J. Swift Gulliver II. iii. ii. 20 A Pudding [cut] into a Cycloid. 1812 J. Playfair Outl. Nat. Philos. I. 128 The line in which a heavy body descends in the least time from one given point to another..is an arch of a cycloid... Hence the cycloid is called the line of swiftest descent. b. companion to the cycloid: the curve formed by successive positions of the point of intersection of a horizontal line drawn through a fixed point in the circumference of the rolling circle with a vertical line through its point of contact with the (horizontal) line on which it rolls. ΚΠ 1837 W. Whewell Hist. Inductive Sci. II. viii. ii. 307 The curve might be of the nature of that which is called the companion to the cycloid. 2. Zoology. A cycloid fish: see cycloid adj. ΘΚΠ the world > animals > fish > parts of fish > [noun] > scales or parts of > fish having > fish having circular scales or cycloid cycloidean1836 cycloid1847 1847 D. T. Ansted Anc. World x. 246 Two orders of Fishes..the Ctenoids and Cycloids. 3. Psychiatry. A person characterized by a tendency to alternate between exhilaration and depression. Also attributive or as adj. ΘΚΠ the world > health and disease > mental health > mental illness > degree or type of mental illness > [noun] > mania > manic depression > person manic-depressive1902 cycloid1925 cyclothyme1925 cyclothymic1925 the world > health and disease > mental health > mental illness > degree or type of mental illness > [adjective] > affected with mania > specifically in psychiatry > manic-depressive > liable to manic depression cycloid1925 cyclothyme1925 cyclothymic1925 syntonic1925 1925 W. J. H. Sprott tr. E. Kretschmer Physique & Char. xi. 127 In an adverse situation the cycloid is either sorrowful or hot-headed, but he is never in the very least nervous. 1927 D. K. Henderson & R. D. Gillespie Text-bk. Psychiatry ix. 190 The ‘syntonic’ or ‘cycloid’ personality, in which, if mental illness develops, it tends to be of the manic-depressive kind. 1929 F. H. Garrison Introd. Hist. Med. (ed. 4) 679 Cycloids are cheerful, temperamental, well adjusted to the business world, but liable to sudden alternations of exhilaration and depression. 1943 H. Read Educ. through Art iv. 76 The ‘depressive cycloid’ temperament is certainly our old friend the melancholic humour. This entry has not yet been fully updated (first published 1893; most recently modified version published online March 2022). cycloidadj. Etymology: < Greek κυκλοειδής, κυκλώδης circular: see cycle n.¹ and -oid suffix.Previous versions of the OED give the stress as: ˈcycloid. Resembling a circle; spec. in Zoology (a) of a somewhat circular form, with concentric striations; applied to the scales of certain fishes; (b) belonging to the Cycloidei, or order of fishes with cycloid scales. ΘΚΠ the world > animals > fish > parts of fish > [adjective] > having scales > of specific type lepidoid1836 cycloid1847 ganoid1847 ctenoid1851 the world > animals > fish > parts of fish > [adjective] > having scales > of scales of specific type fulcral1809 placoid1842 cycloid1847 ctenoid1872 cycloidal1872 1847 D. T. Ansted Anc. World iv. 62 The remaining two groups [of Fishes] are called respectively Ctenoid..and Cycloid..from the shape and structure of the scale. 1851 G. F. Richardson Introd. Geol. (1855) 283 Nearly all the cycloid genera..are extinct. 1872 H. A. Nicholson Man. Palæontol. 326 Scales cycloid or rhomboid. This entry has not yet been fully updated (first published 1893; most recently modified version published online June 2019). < n.adj.1661adj.1847
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