The Collaborative International Dictionary of English v.0.48:

Treble \Tre"ble\, adv.
   Trebly; triply. [Obs.] --J. Fletcher.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Treble \Tre"ble\, n. [" It has been said to be a corruption of
   triplum [Lat.], a third part, superadded to the altus and
   bassus (high and low)." --Grove.] (Mus.)
   The highest of the four principal parts in music; the part
   usually sung by boys or women; soprano.
   [1913 Webster]

   Note: This is sometimes called the first treble, to
         distinguish it from the second treble, or alto, which
         is sung by lower female voices.
         [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Treble \Tre"ble\, v. t. [imp. & p. p. Trebled; p. pr. & vb. n.
   Trebling.]
   1. To make thrice as much; to make threefold. "Love trebled
      life." --Tennyson.
      [1913 Webster]

   2. To utter in a treble key; to whine. [Obs.]
      [1913 Webster]

            He outrageously
            (When I accused him) trebled his reply. --Chapman.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Treble \Tre"ble\, a. [OE. treble threefold, OF. treble, treible,
   L. triplus. See Triple.]
   1. Threefold; triple.
      [1913 Webster]

            A lofty tower, and strong on every side
            With treble walls.                    --Dryden.
      [1913 Webster]

   2. (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.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Treble \Tre"ble\, v. i.
   To become threefold. --Swift.
   [1913 Webster]

WordNet (r) 3.0 (2006):

treble
    adj 1: having or denoting a high range; "soprano voice";
           "soprano sax"; "the boy still had a fine treble voice";
           "the treble clef" [syn: soprano, treble]
    2: three times as great or many; "a claim for treble (or triple)
       damages"; "a threefold increase" [syn: treble, threefold,
       three-fold, triple]
    3: having three units or components or elements; "a ternary
       operation"; "a treble row of red beads"; "overcrowding made
       triple sessions necessary"; "triple time has three beats per
       measure"; "triplex windows" [syn: ternary, treble,
       triple, triplex]
    4: having more than one decidedly dissimilar aspects or
       qualities; "a double (or dual) role for an actor"; "the
       office of a clergyman is twofold; public preaching and
       private influence"- R.W.Emerson; "every episode has its
       double and treble meaning"-Frederick Harrison [syn: double,
       dual, twofold, two-fold, treble, threefold, three-
       fold]
    n 1: the pitch range of the highest female voice [syn:
         soprano, treble]
    v 1: sing treble
    2: increase threefold; "Triple your income!" [syn: triple,
       treble]