Breakbeat

Breakbeat (sometimes breakbeats or breaks) is a term used to describe a collection of sub-genres of electronic music, usually characterized by the use of a non-straightened 4/4 drum pattern (as opposed to the steady beat of house or trance). These rhythms may be characterised by their intensive use of syncopation and polyrhythms.

Source : http://en.wikipedia.org/wiki/Breakbeat