- clef (n.)
- 1570s in a musical sense, from Middle French clef (12c.) "key, musical clef, trigger," from a figurative or transferred use of classical Latin clavis, which had only the literally sense "key" (see slot (n.2)). In the Middle Ages, the Latin word was used in the Guidonian system for "the lowest note of a scale," which is its basis (see keynote). The most common is the treble or G-clef, denoting the G above middle C on the piano.