1. a surface having parabolic sections parallel to a single coordinate axis and elliptic sections perpendicular to that axis;

The Collaborative International Dictionary of English v.0.48:

Paraboloid \Pa*rab"o*loid\ (-loid), n. [Parabola + -oid: cf. F. parabolo["i]de.] (Geom.) The solid generated by the rotation of a parabola about its axis; any surface of the second order whose sections by planes parallel to a given line are parabolas. [1913 Webster] Note: The term paraboloid has sometimes been applied also to the parabolas of the higher orders. --Hutton. [1913 Webster]The Collaborative International Dictionary of English v.0.48:

Conoid \Co"noid\ (k[=o]"noid), n. [Gr. kwnoeidh`s conical; kw^nos cone + e'i^dos form: cf. F. cono["i]de.] 1. Anything that has a form resembling that of a cone. [1913 Webster] 2. (Geom.) (a) A solid formed by the revolution of a conic section about its axis; as, a parabolic conoid, elliptic conoid, etc.; -- more commonly called paraboloid, ellipsoid, etc. (b) A surface which may be generated by a straight line moving in such a manner as always to meet a given straight line and a given curve, and continue parallel to a given plane. --Math. Dict. [1913 Webster]WordNet (r) 3.0 (2006):

paraboloid n 1: a surface having parabolic sections parallel to a single coordinate axis and elliptic sections perpendicular to that axis