"three times, triple," c. 1300, from Old French treble (12c.), from Latin triplus "threefold" (see triple). Related: Trebly.
"to multiply by three," early 14c., from Old French trebler, from treble "triple" (see treble (adj.)). Related: Trebled; trebling.
I recollect once talking with one of the first men in America, who was narrating to me the advantages which might have accrued to him if he had followed up a certain speculation, when he said, "Sir, if I had done so, I should not only have doubled and trebled, but I should have fourbled and fivebled my money." [Capt. Marryat, "A Diary in America," 1839]
"highest part in music, soprano," mid-14c., from Anglo-French treble, Old French treble "a third part," noun use of adjective (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).