1560s, from Late Latin trapezium, from Greek trapezion "irregular quadrilateral," literally "a little table," diminutive of trapeza "table," from tra- "four" (see four) + peza "foot, edge," related to pous (see foot (n.)). Before 1540s, Latin editions of Euclid used the Arabic word helmariphe. As the name of a bone in the wrist, it is recorded from 1840.
trapezium tra·pe·zi·um (trə-pē'zē-əm)
n. pl. tra·pe·zi·ums or tra·pe·zi·a (-zē-ə)
A quadrilateral having no parallel sides.
A bone in the wrist at the base of the thumb, articulating with the first and second metacarpal, scaphoid, and trapezoid bones.