1. (of a person) unrestrained and violent

- rampant aggression

Similar word(s): uncontrolled

2. standing on the left hind leg with forelegs elevated and head (usually in profile)

- a lion rampant

Similar word(s): erect, upright, vertical, rearing

3. widespread, common (especially of unpleasant or harmful things).

- a rampant growth of weeds

Similar word(s): abundant, rife