adjective

1. growing luxuriantly; flourishing rampant plants
2. spreading unchecked; widespread; rife
3. violent and uncontrollable in action, manner, speech, etc.
4. Archit. having one abutment higher than the other: said of an arch
5. 1. rearing up on the hind legs
   2. Heraldry depicted thus in profile, with one forepaw raised above the other a lion rampant

Etymology: ME < OFr, prp. of ramper: see ramp