What does 'ottava' signify in music terminology?

In music terminology, 'ottava' is derived from the Italian word for 'octave,' and it refers specifically to the interval of an octave, which spans eight diatonic scale degrees. This term is commonly used in musical notations to indicate that a passage should be played one octave higher or lower than written. For instance, when encountering '8va' above a note, it instructs the musician to play that section in a higher octave, whereas '8vb' indicates playing in a lower octave. This understanding of 'ottava' allows musicians to effectively communicate the desire for a specific pitch range in performances, enhancing the expressiveness and texture of the music.