An octave is a musical interval of eight notes. Sing from “do” to “do” — on key — and you will have an octave.

Like octagon and octopus, the key to an octave is “eight.” An octave may be the entire eight-note scale, or just the bottom and top notes, like C and C. Octave can also refer to an eight-line group in an Italian sonnet, or an eight-day festival; in fact, the word comes from the Latin expression octava dies, meaning “eighth day” — as in the eighth festival day after a feast. The ave in octave is usually pronounced “iv.”

Definitions of octave
  1. noun
    a musical interval of eight tones
    synonyms: musical octave
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    type of:
    interval, musical interval
    the difference in pitch between two notes
  2. noun
    a rhythmic group of eight lines of verse
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    type of:
    a fixed number of lines of verse forming a unit of a poem
  3. noun
    a feast day and the seven days following it
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    type of:
    church festival, religious festival
    a festival having religious significance
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