trapezoid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A quadrilateral having two parallel sides.
• noun Chiefly British A trapezium.
• noun Anatomy A small bone in the wrist, situated near the base of the index finger.
• noun Sports An area in the shape of a trapezoid marked behind the goal line and the goal in ice hockey, where the goalie is allowed to play the puck.

from The Century Dictionary.

• noun In anthropology, a type of cranium with somewhat flattened vertex and basal region which are approximately in parallel planes.
• Having the shape of a trapezoid. See II., 1.
• noun In geometry, a plane four-sided figure having two of its opposite sides parallel, and the other two not so.
• noun In anatomy and zoology, the trapezoid bone, one of the bones of the wrist, so called from its shape; the second one of the distal row of carpal bones, on the radial or thumb side, between the trapezium and the magnum, in special relation with the head of the second metacarpal bone; carpale II. of the typical carpus. Also called multangulum minus, and trapezoides, trapezoideum. See cuts under Artiodactyla, pisiform, hand, and scapholunar.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Having the form of a trapezoid; trapezoidal.
• adjective (Anat.) Of or pertaining to the trapezoid ligament.
• noun (Geom.) A plane four-sided figure, having two sides parallel to each other.
• noun (Anat.) A bone of the carpus at the base of the second metacarpal, or index finger.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun geometry A (convex) quadrilateral with two (non-adjacent) parallel sides.
• noun anatomy The trapezoid bone of the wrist.
• noun geometry, UK, obsolete A convex quadrilateral with no sides parallel and no equal sides.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a quadrilateral with two parallel sides
• noun the wrist bone between the trapezium and the capitate bones