Rampant means extending rapidly without restraint, raging.
Rampant comes under adjective.
Synonyms: pandemic, prevalent, raging, rife, uncontrollable, universal, widespread, epidemic, unchecked, ungovernable, unrestrained.
Antonyms: checked, curbed, restrained.
Our manager was pleased with the rampant growth that we have experienced this year.
Corruption is rampant in many places of government bodies.
Swine Flu would have been much easier to control when it first started, but now it is spreading rampantly.