|pestə|lenchəl adjective
Etymology: Middle English pestilencial, from Medieval Latin pestilentialis, from Latin pestilentia pestilence + -alis -al
1.
a. : causing or tending to cause pestilence : deadly
a pestilential malignancy in the air — Jonathan Swift
b. : of, relating to, or having the characteristics of a pestilence
pestilential diseases
2. : morally harmful or injurious : pernicious
blow up the blind rage of the populace with a continued blast of pestilential libels — Edmund Burke
3. : giving rise to vexation or annoyance : irritating
the pestilential nuisances who write for autographs — W.S.Gilbert
• pes·ti·len·tial·ly -chəlē, -li adverb