Noun

1. An interval of eight tones on a diatonic scale, representing a doubling or halving in pitch.

   The melody jumps up an octave at the beginning, then later drops back down an octave.

   The singer was known for astounding clarity over her entire five-octave range.

2. The pitch an octave higher than a given pitch.

   The bass starts on a low E, and the tenor comes in on the octave.

3. A poetic stanza consisting of eight lines; usually used as one part of a sonnet.
4. The eighth defensive position, with the sword hand held at waist height, and the tip of the sword out straight at knee level.
5. The day that is one week after a feast day in the Latin Rite of the Catholic Church.
6. An eight day period beginning on a feast day in the Latin Rite of the Catholic Church.

See also

• interval
• unison
• second
• third
• fourth
• fifth
• sixth
• seventh