c.1300, "pack of animals," possibly related to Middle English rablen "speak in a rapid, confused manner," probably imitative of hurry and confusion (cf. Middle Dutch rabbelen, Low German rabbeln "to chatter"). Meaning "tumultuous crowd of people" is first recorded 1510s; applied contemptuously to the common or low part of any populace from 1550s. Rabble-rousing first attested 1802 in Sydney Smith.