Translation guide
Describes something spreading quickly and uncontrollably, often in a negative sense. Japanese uses different words depending on what is rampant: crime, disease, plants, rumors, etc.
Crime is rampant.
Weeds are rampant.
To say that something bad is happening a lot and is hard to control.
Literally 'go sideways', used for negative things like crime, fraud, or bad behavior spreading widely. Often used in news.
Fraud is rampant in this area.
Spreading like a vine, used for diseases, bad influences, or negative phenomena. Stronger nuance of pervasive spread.
Infectious diseases are rampant.
Very formal/literary, meaning 'to be at its height of rampancy'. Used for epidemics or evil forces.
A plague was rampant.
To describe vegetation that has grown very densely and wildly.
To say that rumors or gossip are spreading everywhere.
To describe wild, unchecked behavior or feelings.
English 'rampant' covers many situations, but Japanese requires different words for plants, diseases, rumors, etc. Using 蔓延する for weeds sounds odd; use 生い茂る instead.
Various speculations about the truth of the incident were rampant.