Source : Webster's Revised Unabridged Dictionary (1913)

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 : WordNet®

trapezium
     n 1: a quadrilateral with no parallel sides [ant: {parallelogram}]
     2: a multiple star in the constellation of Orion [syn: {the
        Trapezium}]
     3: the wrist bone on the thumb side of the hand that
        articulates with the 1st and 2nd metacarpals [syn: {trapezium
        bone}, {os trapezium}]
     [also: {trapezia} (pl)]

trapezia
     See {trapezium}