Additive rhythm and divisive rhythm

In music, additive and divisive are terms used to distinguish two types of both rhythm and meter.

A divisive (or, more commonly, multiplicative) rhythm is a rhythm in which a larger period of time is divided into smaller rhythmic units or, conversely, some integer unit is regularly multiplied into larger, equal units; this can be contrasted with additive rhythm, in which larger periods of time are constructed by concatenating (joining end to end) a series of units into larger units of unequal length, such as a 5/8 meter produced by the regular alternation of 2/8 and 3/8 (London 2001, §I.8). When applied to meters, the terms "perfect" and "imperfect" are sometimes used as the equivalents of "divisive" and "additive", respectively (Read 1969, 150).