n. The quality or state of being rampant; excessive action or development; exuberance; extravagance. “They are come to this height and rampancy of vice.” South. [ 1913 Webster ]

a. [ F., p. pr. of ramper to creep. See Ramp, v. ] 1. Ramping; leaping; springing; rearing upon the hind legs; hence, raging; furious. [ 1913 Webster ]

The fierce lion in his kind
Which goeth rampant after his prey. Gower. [ 1913 Webster ]

[ The ] lion . . . rampant shakes his brinded mane. Milton. [ 1913 Webster ]

2. Ascending; climbing; rank in growth; exuberant. [ 1913 Webster ]

The rampant stalk is of unusual altitude. I. Taylor. [ 1913 Webster ]

3. (Her.) Rising with fore paws in the air as if attacking; -- said of a beast of prey, especially a lion. The right fore leg and right hind leg should be raised higher than the left. [ 1913 Webster ]

Rampant arch. (a) An arch which has one abutment higher than the other. (b) Same as Rampant vault, below. --
Rampant gardant (Her.), rampant, but with the face turned to the front. --
Rampant regardant, rampant, but looking backward. --
Rampant vault (Arch.), a continuous wagon vault, or cradle vault, whose two abutments are located on an inclined plane, such as the vault supporting a stairway, or forming the ceiling of a stairway. [ 1913 Webster ]

adv. In a rampant manner. [ 1913 Webster ]