Tra·pe·zi·um n.; pl. E. Trapeziums L. Trapezia
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.
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