trapezium (n.) Look up trapezium at Dictionary.com
1560s, from Late Latin trapezium, from Greek trapezion "irregular quadrilateral," literally "a little table," diminutive of trapeza "table, dining table," from tra- "four" (see four) + peza "foot, edge," related to pous (see foot (n.)). Before 1540s, Latin editions of Euclid used the Arabic-derived word helmariphe. As the name of a bone in the wrist, it is recorded from 1840.