adj. 1. a. Causing or likely to cause epidemic disease: a pestilent swamp. b. Infectious or epidemic: a pestilent disease. c. Archaic Tending to cause death; deadly. 2. Morally or socially harmful; pernicious: pestilent writings. 3. Causing annoyance or disapproval: a pestilent fool. [Middle English, from Old French, from Latin pestilēns, pestilent-, from pestis, pestilence; see PEST.] |
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