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]

Moby Thesaurus II by Grady Ward, 1.0:

96 Moby Thesaurus words for "treble":
   accompaniment, air, alto, aria, baritone, bass, basso continuo,
   basso ostinato, bassus, bourdon, bravura, burden, canto, cantus,
   cantus figuratus, cantus planus, chest voice, choral, choric,
   coloratura, continuo, contralto, countertenor, cube, descant,
   dramatic, drone, drone bass, falsetto, figured bass, ground bass,
   head register, head tone, head voice, heroic, high, high-pitched,
   high-sounding, high-toned, hymnal, lay, line, liturgical, lyric,
   male alto, measure, melodia, melodic line, melody, mezzo-soprano,
   multiply by three, note, operatic, part, piercing, piping,
   plain chant, plain song, prick song, psalmic, psalmodial,
   psalmodic, refrain, sacred, sharp, shrill, singing, solo,
   solo part, song, soprano, soprano part, strain, tenor, tern,
   ternal, ternary, ternate, thin, thorough bass, three-ply,
   threefold, trilogic, trinal, trine, triple, triplex, triplicate,
   tune, undersong, vocal, voce, voce di petto, voce di testa, voice,
   voice part