a musical interval of eight notes on the diatonic scale
the whole series of notes or piano, organ, etc keys within this interval that form the unit of the modern diatonic scale
a note separated from a lower note by this interval
a group of eight lines of verse, esp the first eight of a sonnet
an eight-day period of religious observances beginning with a festival day, or the final day of this period
in fencing, the last of eight parrying positions
any group of eight
[Middle English from Latin octava, fem of octavus eighth, from octo eight]