The Collaborative International Dictionary of English v.0.48:

Cylindroid \Cyl"in*droid\ (s?l"?n-droid), n. [Gr. ky`lindros
   cylinder + -oid: cf. F. cylindro["i]de.]
   1. A solid body resembling a right cylinder, but having the
      bases or ends elliptical.
      [1913 Webster]

   2. (Geom.) A certain surface of the third degree, described
      by a moving straight line; -- used to illustrate the
      motions of a rigid body and also the forces acting on the
      body.
      [1913 Webster]