treble (adj.) Look up treble at Dictionary.com
late 14c., "three times, triple," from Old French treble (12c.), from Latin triplus (see triple).
treble (v.) Look up treble at Dictionary.com
early 14c., "to multiply by three," from Old French trebler, from treble (see treble (adj.)). Related: Trebled; trebling.
treble (n.) Look up treble at Dictionary.com
"highest part in music, soprano," mid-14c., from Anglo-French treble, Old French treble (see treble (adj.)). In early contrapuntal music, the chief melody was in the tenor, and the treble was the "third" part above it (after the alto).