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

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]

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]