Definitions

1. 1.interval (distance in space)
2. 2.interval (period of time)
3. 3.interval (difference (a ratio or logarithmic measure) in pitch between two notes, often referring to those two pitches themselves (otherwise known as a dyad))
4. 4.interval training, fartlek (training based upon a series of high-intensity workouts interspersed with rest or relief periods)

Forms