Of the nature or shape of a pyramid; resembling a pyramid. Also figurative or in figurative context (cf. pyramid, n. 8).

Triangular in section, triquetrous: now esp. in Zoology and Botany.

Resembling a pyramid, pyramidal; composed of one or more pyramids. In later use chiefly Botany and Zoology.

= pyramidal, adj. 2a.

A pyramid. (Only attributive or in combination.)

= pyramidal, adj. 2a.

Having three edges, as a prism or pyramid; three-edged, trihedral, triquetrous.

composed of pyramids; formed into a pyramid; pyramidal.

Three-sided triangular; in Natural History of triangular cross-section, three-edged, trihedral, triangularly prismatic or pyramidal.

trihedral angle or trihedral quoin, a solid angle formed by three surfaces meeting at a point.

= pyramidoidal, adj. 1.