Trapezium
Trapezium , noun
[New Latin, from Greek {not transcribed} a little table, an irregular four-sided figure, dim. of {not transcribed} a table, for {not transcribed}; {not transcribed} (see Tetra-) + {not transcribed} foot, akin to {not transcribed} foot; hence, originally, a table with four feet. See Foot.]
1.
(Geometry) A plane figure bounded by four right lines, of which no two are parallel.
2.
(a) (Anatomy) A bone of the carpus at the base of the first metacarpal, or thumb.
(b)
(Anatomy) 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.