noun. In anatomy, the triangular lobule on the median surface of the cerebrum, bounded by the parieto-occipital and calcarine fissures. See cerebrum.

noun. In entomology, a triangular part of the hemielytrum found in certain heteropterous insects, inserted like a wedge on the outer side between the corium and the membrane.

noun. any shape that is triangular in cross section

"This first writing system, cuneiform -- from the Latin word cuneus, for wedge -- was invented by the region's first powerful culture, the non-Semitic Sumerians, during the fourth millennium BC."

triangle  trigon  trilateral