Origin: NL, fr. Gr. A little table, an irregular four-sided figure, dim. Of a table, for; (see Tetra-) – foot, akin to foot; hence, originally, a table with four feet. See Foot.
1. (Science: geometry) A plane figure bounded by four right lines, of which no two are parallel.
2. (Science: anatomy) A bone of the carpus at the base of the first metacarpal, or thumb. A region on the ventral side of the brain, either just back of the pons Varolii, or, as in man, covered by the posterior extension of its transverse fibres.