An octave is a musical INTERVAL that spans EIGHT notes on the musical scale, and is also referred to as an EIGHTH. It is the INTERVAL between two notes that have the same letter name but are separated by one or more octaves. An octave is also the distance between two notes that have the same pitch but are separated by EIGHT notes on the musical scale. The term octave can also refer to a group of EIGHT notes in a scale or a set of EIGHT notes that are repeated in a melody.