Trapezium \Tra*pe"zi*um\, n.; pl. E. Trapeziums, L. Trapezia. [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. (Geom.) A plane figure bounded by four right lines, of which no two are parallel.

2. (Anat.)
   (a) A bone of the carpus at the base of the first metacarpal, or thumb.
   (b) 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 fibers.

Source: Webster's Revised Unabridged Dictionary (1913)