progression

Sequence of numbers each occurring in a specific relationship to its predecessor. An arithmetic progression has numbers that increase or decrease by a common sum or difference (for example, 2, 4, 6, 8); a geometric progression has numbers each bearing a fixed ratio to its predecessor (for example, 3, 6, 12, 24); and a harmonic progression has numbers whose reciprocals are in arithmetical progression, for example 1, 1/2, 1/3, 1/4.

progression

Logical movement of two or more chords in succession, either harmonically, with all the notes moving simultaneously, or polyphonically, with each one being part of a continuously moving horizontal melodic line.