octave

From WikiWord, the free dictionary

/ˈɒkteɪv/ English

Definitions

An interval of twelve semitones spanning eight degrees of the diatonic scale, representing a doubling or halving in pitch frequency.“The melody jumps up an octave at the beginning, then later drops back down an octave.”
The pitch an octave higher than a given pitch.“The bass starts on a low E, and the tenor comes in on the octave.”
A coupler on an organ which allows the organist to sound the note an octave above the note of the key pressed (cf sub-octave)
A poetic stanza consisting of eight lines; usually used as one part of a sonnet.