cyclideGeom.|ˈsaɪklɪd, ˈsɪklaɪd| [a. F. cyclide, f. cycle.] ‘The envelope of a sphere whose centre moves on a fixed quadric, and which cuts a fixed sphere orthogonally’ (Salmon). 1874Salmon Analyt.Geom. Three Dim. 496. 1881 H. Hart in Athenæum 23 Apr. 563/2 On the Five Focal Quadrics of a Cyclide.