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.

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.

• (geometry) (British) A four-sided polygon with two non-adjacent parallel sides (called a trapezoid in US English).
  
• (geometry) (US) A four-sided polygon with no two sides parallel (known as a trapezoid in British English).
  
• 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 fibers.