nounDate: 1743 a quadric surface whose sections by planes parallel to one coordinate plane are ellipses while those sections by planes parallel to the other two are hyperbolas if proper orientation of the axes is assumed • hyperboloidaladjective

Hyperboloid Hy*per"bo*loid, n. [Hyperbola + -oid: cf. F. hyperbolo["i]de.] (Geom.) A surface of the second order, which is cut by certain planes in hyperbolas; also, the solid, bounded in part by such a surface. Hyperboloid of revolution, an hyperboloid described by an hyperbola revolving about one of its axes. The surface has two separate sheets when the axis of revolution is the transverse axis, but only one when the axis of revolution is the conjugate axis of the hyperbola.