a. [f. prec. + -AL.]
1. Geom. Pertaining to, or of the form of, a conoid (in its various senses).
Conoidal cusps (in Optics), the name given by Sir W. R. Hamilton to the singular points or conical points of the wave-surface.
1571. Digges, Pantom., IV. Pref. T j. Not onely … Theorems of spherall solides, but also of Conoydall, Parabollical, Hyperbollical, and Ellepseycal circumscribed and inscribed bodies.
1837. Babbage, Bridgw. Treat., viii. 103. The curve surface … had four conoidal cusps at each of which there were, consequently, an infinite number of tangent planes.
1865. Aldis, Solid Geom., § 144. A conoidal surface is a surface generated by a straight line which always meets a fixed straight line, is parallel to a fixed plane, and meets a fixed curve.
2. in gen. use. Approaching in shape to a cone; nearly but not exactly conical.
1741. Monro, Anat. (ed. 3), 25. The Figure … is somewhat conoidal.
1842. H. Miller, O. R. Sandst., xi. (ed. 2), 233. Conoidal hills, bare of soil.
1865. Pall Mall G., 29 Aug., 10/2. The new musket, adapted to conoidal shot.
Hence Conoidally adv.
