a. and sb. [f. as prec. + -OID.] a. adj. Resembling or approaching the form of a tetrahedron. b. sb. Geom. The envelope of a quadric surface which touches eight given straight lines.
1889. Cayley’s Math. Papers I. 587, note. The surface here considered, the Tetrahedroid, is the general homographic transformation of the wave surface.
1899. Geog. Jrnl., March, 251. Causes, which … would go in the direction of producing tetrahedral, or tetrahedroid, deformation.
