What does "treble" mean?

Treble: (Mus.) (a) Acute; sharp; as, a treble sound. Bacon. (b) Playing or singing the highest part or most acute sounds; playing or singing the treble; as, a treble violin or voice.

Additional senses

  1. 2.Trebly; triply. [Obs.] J. Fletcher.
  2. 3.The highest of the four principal parts in music; the part usually sung by boys or women; soprano. Note: This is sometimes called the first treble, to distinguish it from the second treble, or alto, which is sung by lower female voices.
  3. 4.To make thrice as much; to make threefold. "Love trebled life." Tennyson.
  4. 5.To utter in a treble key; to whine. [Obs.] He outrageously (When I accused him) trebled his reply. Chapman.
  5. 6.To become threefold. Swift.

Sources