Rampant means spreading wildly and uncontrollably, growing or occurring in a way that's hard to stop. When weeds grow rampant in a garden, they shoot up everywhere, choking out the vegetables and flowers you actually wanted. When rumors spread rampant through a school, they move from student to student so quickly that soon everyone believes something that might not even be true.

The word suggests something that's both widespread and out of control. A few dandelions in your lawn isn't rampant growth, but when they take over the entire yard, that's rampant. Disease can run rampant through a population. Crime can be rampant in a city. Corruption can grow rampant in a government.

You'll also see rampant used in heraldry, the system of family coats of arms. A lion rampant stands on its hind legs with its front paws raised, as if ready to attack. This fierce, upright pose became a symbol of strength and courage on shields and flags throughout Europe.

When something is rampant, it has escaped normal limits and boundaries. It's the difference between a few kids whispering during class and chaos breaking out across the entire room.