noun oc·tave \ˈäk-tiv, -təv, -ˌtāv\

music : the difference in sound between the first and eighth note on a musical scale

Full Definition of OCTAVE

:  an 8-day period of observances beginning with a festival day
a :  a stanza of eight lines :  ottava rima
b :  the first eight lines of an Italian sonnet
a :  a musical interval embracing eight diatonic degrees
b :  a tone or note at this interval
c :  the harmonic combination of two tones an octave apart
d :  the whole series of notes, tones, or digitals comprised within this interval and forming the unit of the modern scale
e :  an organ stop giving tones an octave above those corresponding to the keys
:  the interval between two frequencies (as in an electromagnetic spectrum) having a ratio of 2 to 1
:  a group of eight

Examples of OCTAVE

  1. He sang the song an octave lower.

Origin of OCTAVE

Middle English, from Anglo-French, from Medieval Latin octava, from Latin, feminine of octavus eighth, from octo eight — more at eight
First Known Use: 14th century
OCTAVE Defined for Kids


noun oc·tave \ˈäk-tiv\

Definition of OCTAVE for Kids

:  a space of eight steps between musical notes
:  a tone or note that is eight steps above or below another note or tone
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