Music. a tone on the eighth degree from a given tone. the interval encompassed by such tones. the harmonic combination of such tones. a series of tones, or of keys of an instrument, extending through this interval.
a pipe-organ stop whose pipes give tones an octave above the normal pitch of the keys used.
a series or group of eight.
Also called octet. Prosody. a group of eight lines of verse, especially the first eight lines of a sonnet in the Italian form. Compare sestet (def 1). a stanza of eight lines.