treble

Concise Oxford English Dictionary © 2008 Oxford University Press:
treble1

▶adjective

• 1 consisting of three parts.

• 2 multiplied or occurring three times.

▶predeterminer three times as much or as many. ▶noun

• 1 Brit. three sporting victories or championships in the same season, event, etc.

• 2 Darts a hit on the narrow ring enclosed by the two middle circles of a dartboard, scoring treble.

• 3 Brit. a system of betting in which the winnings and stake from the first bet are transferred to a second and then (if successful) to a third.

• 4 a thing which is three times larger than usual or is made up of three parts.

▶pronoun an amount which is three times as large as usual. ▶verb make or become treble.

– origin ME: via OFr. from L. triplus (see triple).

Concise Oxford English Dictionary © 2008 Oxford University Press:
treble2

▶noun

• 1 a high-pitched voice, especially a boy's singing voice.

• 2 [as modifier] denoting a relatively high-pitched member of a family of instruments.

  ■ (also treble bell) the smallest and highest-pitched bell of a ring or set.

• 3 the high-frequency output of a radio or audio system, corresponding to the treble in music.

– origin ME: from treble1, because it was the highest part in a three-part contrapuntal composition.