The definition of an octave is a progression of eight notes on a musical scale, or the notes at the beginning and end of the progression.(noun)
Two musical notes which are eight tones apart on a scale are an example of an octave.
See octave in Webster's New World College Dictionary
Origin: OFr < L octava, fem. of octavus, eighth < octo, eight
See octave in American Heritage Dictionary 4
Origin: Middle English, eighth day after a feast day
Origin: , from Old French
Origin: , from Medieval Latin octāva (diēs)
Origin: , from Latin
Origin: , feminine of octāvus, eighth
Origin: , from octō, eight; see oktō(u) in Indo-European roots.
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