What does "octave" mean?

Octave: (Mus.) (a) The eighth tone in the scale; the interval between one and eight of the scale, or any interval of equal length; an interval of five tones and two semitones. (b) The whole diatonic scale itself. Note: The ratio of a musical tone to its octave above is 1:2 as regards the number of vibrations producing the tones.

Additional senses

  1. 2.(Poet.) The first two stanzas of a sonnet, consisting of four verses each; a stanza of eight lines. With mournful melody it continued this octave. Sir P. Sidney. Double octave. (Mus.) See under Double. -- Octave flute (Mus.), a small flute, the tones of which range an octave higher than those of the German or ordinary flute; -- called also piccolo. See Piccolo.
  2. 3.A small cask of wine, the eighth part of a pipe.
  3. 4.Consisting of eight; eight. Dryden.

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