US definition: * Trapezium : A quadrilateral with none of its sides parallel to each other. * Trapezoid: A quadrilateral with only one pair of opposite sides parallel. read more
Trapezium is a synonym of trapezoid. As nouns the difference between trapezoid and trapezium is that trapezoid is (geometry) a (convex) quadrilateral with two (non-adjacent) parallel sides while trapezium is (geometry|british) a four-sided polygon with two sides parallel; a trapezoid (modern sense). read more