trapezium
noun (- (British English) (North American English trapezoid)
a flat shape with four straight sides, one pair of opposite sides being parallel (= the same distance apart at every point) and the other pair not parallel 梯形 
- (North American English) (British English trapezoid)
a flat shape with four straight sides, none of which are parallel (= the same distance apart at every point) 不规则四边形
Word Originlate 16th cent.: via late Latin from Greek trapezion, from trapeza ‘table’.