Geom. [f. CONIC + -OID, after ellipsoid, etc.] In Solid Geometry: A surface of which every plane section is a conic (see CONIC B. 2); a surface of the second degree, a quadric surface or quadric: e.g., a sphere, ellipsoid, cone, paraboloid, or hyperboloid.
1863. Frost & Wolstenholme, Solid Geom., § 204. A surface of the second degree shall in future be denominated a Conicoid. Ibid., § 205. Properties of conicoids deduced by the modular and umbilical methods of generation.
1865. Aldis, Solid Geom., v. § 52. Surfaces whose equations are of the second degree in (x, y, z) are called Quadrics, or, following the analogy of the terms ellipsoid, &c., Conicoids.
1880. G. S. Carr, Synopsis, I. § 5599. A conicoid is a surface every plane section of which is a conic.
