|1.||a. the interval between two musical notes one of which has twice the pitch of the other and lies eight notes away from it counting inclusively along the diatonic scale|
|b. one of these two notes, esp the one of higher pitch|
|c. perfect diminished See also interval (as modifier): an octave leap|
|2.||prosody a rhythmic group of eight lines of verse|
|3.||a. a feast day and the seven days following|
|b. the final day of this period|
|4.||the eighth of eight basic positions in fencing|
|5.||any set or series of eight|
|6.||consisting of eight parts|
|[C14: (originally: eighth day) via Old French from Medieval Latin octāva diēs eighth day (after a festival), from Latin octo eight]|
An interval between musical notes in which the higher note is six whole tones, or twelve half tones, above the lower. From the standpoint of physics, the higher note has twice the frequency of the lower. Notes that are an octave apart, or a whole number of octaves apart, sound in some ways like the same note and have the same letter for their names.
in music, an interval whose higher note has a sound-wave frequency of vibration twice that of its lower note. Thus the international standard pitch A above middle C vibrates at 440 hertz (cycles per second); the octave above this A vibrates at 880 hertz, while the octave below it vibrates at 220 hertz.
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