Definition of: interval

(in′tər·vəl) noun
1. An open space between two objects; distance between points; intervening room.
2. The degree of difference between objects.
3. The time that intervenes between two events or periods or between a state or condition and its recurrence.
4. U.S. & Can. Intervale.
5. Music a The difference in pitch between two tones sounded in succession. b The difference in pitch of tones sounded at or near the same time.
—augmented interval A musical interval longer than the indicated standard by a half–step or semitone.
—diminished interval An interval that is a half–step shorter than the perfect or minor interval indicated.
—harmonic interval An interval in which the tones are simultaneous.
—inverted interval A simple interval in which the lower tone is transposed an octave upward, or the upper tone an octave downward.
—melodic interval An interval in which the tones are successive.
—perfect interval. An interval admitting of no change without destroying the consonance, as the prime, fourth, fifth, and octave. [<OF entreval, intervalle <L intervallum between the ramparts <inter- between + vallum rampart]
MUSICAL INTERVALS
1. Prime or unison. 2. Augmented prime. 3. Minor second. 4. Major second. 5. Augmented second. 6. Minor third. 7. Major third. 8. Perfect fourth. 9. Augmented fourth. 10. Diminished fifth. 11. Perfect fifth. 12. Augmented fifth. 13. Minor sixth. 14. Major sixth. 15. Augmented sixth. 16. Minor seventh. 17. Major seventh. 18. Diminished octave. 19. Octave. On a keyboard instrument where mechanical limitations make it necessary to make one tone serve for two slightly different ones, some of the intervals above appear identical, as 5 and 6.