adjective
Definition: Referring to a musical note that is one octave higher or lower than the note that is written.
Example: The composer instructed the musicians to play the piece in ottava to achieve a brighter sound.
adverb
Definition: In music, this term refers to playing or singing notes that are one octave higher or lower than what is written on the sheet music.
Example: The musician played the piece in ottava, giving it a brighter sound.