In music, since incomposite means undivided, an incomposite interval (diastēma, German: ungeteilte Intervall), "is a large interval which appears as a melodic step or second in a scale, but which is a skip in other parts of the scale."[1] Aristoxenus says, "Let us assume that in each genus an interval is melodically incomposite if the voice, in singing a melody, cannot divide it into intervals."[2]
For example the augmented second in the harmonic minor scale, on A, occurs as a step between F and G♯, though the equivalent minor third occurs elsewhere, such as a skip between A & C.