Английский Этимологический словарь - treble (adj.)

- 13c., "three times, triple," from O.Fr. treble, from L. triplus (see triple). The verb is early 14c. The noun meaning "highest part in music, soprano" is early 14c., from O.Fr. treble; in early contrapuntal music, the chief melody was in the tenor, and the treble was the "third" part above it (after the alto).