also break-up, "a disruption, dissolution of connection, separation of a mass into parts," 1795, from verbal expression break up "separate, dissolve" (mid-15c.); see break (v.) + up (adv.). The verbal phrase was used of plowland, later of groups, assemblies, etc.; of things (also of marriages, relationships), from mid-18c. Break it up as a command to stop a fight, etc., is recorded from 1936.