/te'treuh hee"dreuhn/ , n. , pl. tetrahedrons, tetrahedra /-dreuh/ .
1. Geom. a solid contained by four plane faces; a triangular pyramid.
2. any of various objects resembling a tetrahedron in the distribution of its faces or apexes.
[ 1560-70; TETRA- + -HEDRON, modeled on LGk tetráedron, n. use of neut. of tetráedros four-sided ]