[oc.tave] n [ME, fr. ML octava, fr. L, fem. of octavus eighth, fr. octo eight--more at eight] (14c) 1: an 8-day period of observances beginning with a festival day
2. a: a stanza of eight lines: ottava rima b: the first eight lines of an Italian sonnet 3 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 digitals
4: the interval between two frequencies (as in an electromagnetic spectrum) having a ratio of
2. to 1
5: a group of eight