(originally) Rearing on both hind legs with the forelegs extended. / (heraldry) Rearing up, especially on its hind leg(s), with a foreleg raised and in profile.

(informal, nonstandard) Rampantly.

Quality of being rampant.

(idiomatic) To go unchecked or without control; to be wild or excessive.

(heraldry, of two animals) Both rampant and facing each other

(heraldry) Sitting with the forefeet lifted up.

In a rampant manner.