rhamphoidn.adj.

Brit.

/ˈramfɔɪd/, U.S.

/ˈræmfɔɪd/

Forms: 1800s– rhamphoid, 1800s– ramphoid.

Origin: A borrowing from Greek, combined with an English element; modelled on a French lexical item. Etymons: Greek ῥάμϕος , -oid suffix.

Etymology: < ancient Greek ῥάμϕος beak, of uncertain origin + -oid suffix, after French ramphoïde, noun ( L.-B. Francœur Cours complet de math. pures (1809) II. vii. iii. 318).

Mathematics.

†A. n.

A rhamphoid cusp. Obsolete.

ΘΚΠ

the world > relative properties > number > geometry > point > [noun] > of intersection or contact > of specific lines or curves

cuspis1646

focus1656

point of reflection1674

umbilicus1704

cuspid1743

cusp1758

rhamphoid1814

biplanar1849

oscnode1852

tacnode1852

tangential of a point1858

cnicnode1869

uniplane1869

unode1869

1814 P. Barlow New Math. & Philos. Dict. at Inflection If after the retrogression the concavity of the two parts lie the same way, it is called a ramphoid,..but if they lie the contrary way, having their convexities towards each other, it is called a ceratoid.

1851 J. Haddon Examples & Solutions Differential Calculus 101 For the ramphoid or cusp of the second species, the values of ^d²y/ _dx² have the same sign.

1873 W. G. Peck Pract. Treat. Differential & Integral Calculus ii. iii. 71 For the ceratoid the values of the second differential coefficient of y have contrary signs, for the ramphoid they have the same sign.

B. adj.

Designating a cusp at which the two branches of the curve lie on the same side of the common tangent, i.e. they have their concavity in the same direction. Contrasted with keratoid adj. 1.

ΚΠ

1841 D. F. Gregory Examples Processes Differential & Integral Calculus i. x. 170 The curve..has at the origin a ramphoid cusp.

1896 J. Edwards Elem. Treat. Differential & Integral Calculus (ed. 3) 232 The product of the roots is x⁷, which is positive or negative according as x is positive or negative. It is therefore ramphoid on the right-hand side of the new y-axis and keratoid on the left-hand side.

1937 Math. Gaz. 21 278 The curve..has a ramphoid cusp.

1994 Amer. Math. Soc. 101 406 We obtain either a smooth locally convex point if the tangent lines have the same direction or a rhamphoid cusp if the directions are different.

This entry has been updated (OED Third Edition, June 2010; most recently modified version published online March 2022).

单词	rhamphoid
释义	rhamphoidn.adj. Brit. /ˈramfɔɪd/, U.S. /ˈræmfɔɪd/ Forms: 1800s– rhamphoid, 1800s– ramphoid. Origin: A borrowing from Greek, combined with an English element; modelled on a French lexical item. Etymons: Greek ῥάμϕος , -oid suffix. Etymology: < ancient Greek ῥάμϕος beak, of uncertain origin + -oid suffix, after French ramphoïde, noun ( L.-B. Francœur Cours complet de math. pures (1809) II. vii. iii. 318). Mathematics. †A. n. A rhamphoid cusp. Obsolete. ΘΚΠ the world > relative properties > number > geometry > point > [noun] > of intersection or contact > of specific lines or curves cuspis1646 focus1656 point of reflection1674 umbilicus1704 cuspid1743 cusp1758 rhamphoid1814 biplanar1849 oscnode1852 tacnode1852 tangential of a point1858 cnicnode1869 uniplane1869 unode1869 1814 P. Barlow New Math. & Philos. Dict. at Inflection If after the retrogression the concavity of the two parts lie the same way, it is called a ramphoid,..but if they lie the contrary way, having their convexities towards each other, it is called a ceratoid. 1851 J. Haddon Examples & Solutions Differential Calculus 101 For the ramphoid or cusp of the second species, the values of ^d²y/ _dx² have the same sign. 1873 W. G. Peck Pract. Treat. Differential & Integral Calculus ii. iii. 71 For the ceratoid the values of the second differential coefficient of y have contrary signs, for the ramphoid they have the same sign. B. adj. Designating a cusp at which the two branches of the curve lie on the same side of the common tangent, i.e. they have their concavity in the same direction. Contrasted with keratoid adj. 1. ΚΠ 1841 D. F. Gregory Examples Processes Differential & Integral Calculus i. x. 170 The curve..has at the origin a ramphoid cusp. 1896 J. Edwards Elem. Treat. Differential & Integral Calculus (ed. 3) 232 The product of the roots is x⁷, which is positive or negative according as x is positive or negative. It is therefore ramphoid on the right-hand side of the new y-axis and keratoid on the left-hand side. 1937 Math. Gaz. 21 278 The curve..has a ramphoid cusp. 1994 Amer. Math. Soc. 101 406 We obtain either a smooth locally convex point if the tangent lines have the same direction or a rhamphoid cusp if the directions are different. This entry has been updated (OED Third Edition, June 2010; most recently modified version published online March 2022). < n.adj.1814
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