TRAPEZIUM

noun a bone of the carpus at the base of the first metacarpal, or thumb.

2. trapezium ·noun a plane figure bounded by four right lines, of which no two are parallel.

3. trapezium ·noun 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.