rampant
1. [ adjective ] unrestrained and violent
Examples:

"rampant aggression"

Related terms: uncontrolled
2. [ adjective ] (heraldry) rearing on left hind leg with forelegs elevated and head usually in profile
Synonyms: rearing
Examples:

"a lion rampant"

Related terms: heraldry erect
Similar spelling:   rampantly
  rampion