a. and sb. [mod. ad. Gr. κωνοειδής cone-shaped, κωνοειδές a conoid: see -OID.]
A. adj. Approaching a cone in shape; more or less conical in shape.
Conoid body: the pineal gland (Syd. Soc. Lex.). Conoid ligament: the posterior fasciculus of the coraco-clavicular ligament, attached above to the conoid tubercle, at the scapular end of the lower surface of the clavicle. Conoid teeth: canine teeth.
1668. Phil. Trans., III. 666. Stretching the surface of it from a Plain to a Conoid figure, within the same Circumference.
1774. Pennant, Tour Scotl. in 1772, 293. Two large conoid cairns.
1828. Stark, Elem. Nat. Hist., II. 42. Shell turreted or conoid.
1836–9. Todd, Cycl. Anat., II. 155/1. The insertion of the … conoid … ligaments.
B. sb.
1. Geom. a. A solid generated by the revolution of a conic section about its axis; a conicoid of revolution (esp. a paraboloid or hyperboloid, the ellipsoids or spheroids being often excluded). This is the κωνοειδές of Archimedes.
[1656. Hobbes, 6 Lessons, v. Wks. 1845, VII. 305. Your comparison of the sphere and conoeides, so far holds good.]
a. 1664. Barrow, in Rigaud, Corr. Sci. Men (1841), II. 34. Concerning the parabolical conoids.
1796. Hutton, Math. Dict., I. 327. In the hyperbolic conoid, the section is an ellipse, when its axis makes with the axis of the solid an angle greater than that made by [this] and the asymptote of the generating hyperbola. Ibid. (1807), Course Math., II. 274. A diving bell, of the form of a parabolic conoid.
1872. Proctor, Ess. Astron., xii. 164. The [zodiacal] light exhibits usually the figure of an oblique conoid.
† b. See quot. Obs.
1730–6. Bailey (folio), Conoid (with Geomet.), a solid Body resembling a Cone, excepting that instead of a perfect Circle, it has for its Base an Ellipsis or some other Curve approaching thereto.
c. A surface generated by a straight line that continues parallel to a fixed plane, and passes through a fixed straight line and a fixed curve. Cf. CONOCUNEUS.
This sense occurs in Fr. conoïde in 1774, and perh. earlier; it is that now usual in Solid Geometry.
1862. Salmon, Geom. of 3 Dim. (1874), § 448. Surfaces generated by lines parallel to a fixed plane. This is a family of surfaces which includes conoids as a particular case. Ibid., § 450. Surfaces generated by lines which meet a fixed axis. This class also includes the family of conoids.
1865. Aldis, Solid Geom., § 144. If the fixed line be perpendicular to the fixed plane…. In this case the surface is called a right conoid.
2. in gen. use. Any body of a shape more or less approaching a cone, esp. one having the form of half a spindle, in which the slant sides from the base to the vertex are curved instead of straight.
1793. Sir G. Shuckburgh, in Phil. Trans., LXXXIII. 76. A steel point or cone, resting in a hollow conoid of bell metal.
1835. Ure, Philos. Manuf., 367. To back off the spiral-coil from the tip of the spindle, and then wind the thread upon it in a shapely conoid.
1868. Proctor, in Daily News, 25 Nov. The conoid used in ordinary rifle practice … passes much more freely through the air, point first, than an ordinary spherical bullet.
1882. Sladen, in Jrnl. Linn. Soc., XVI. 236. Dorsally the centre of the disk is elevated into a sharp conoid.
3. Anat. The pineal gland; = Conoid body: see A.
1828. in Webster.
