Polyrhythm
Two or more different rhythms played at the same time, such as three beats against two.
Also: cross-rhythm
In a polyrhythm, separate rhythmic patterns run together and fit against each other. The simplest is three evenly spaced notes played in the time of two. Much of the drumming of West and Central Africa is built this way, with each drum and bell holding its own pattern. Dancers show the layers in the body. The feet may keep one rhythm while the shoulders, hips or arms mark another. The idea travelled with African peoples to Cuba, Brazil, Haiti and North America.