Adj. or noun
1. Morally or socially harmful; pernicious.
2.a. Bringing or producing plague, esp. bubonic plague; injurious to health, noxious, deadly; pestilent, pestilential.
2.b. Originally: infected with a contagious disease, esp. bubonic plague. Also as noun (with the and pl. concord): such people as a class (obs.). Later: caused by or of the nature of bubonic plague.
2.c. Of an organism, esp. an insect: harmful, destructive.
3. In weakened sense: constituting a nuisance; irritating, annoying.
First a pestiferous caterpillar,
The budding ballerina turned to a butterfly
On her way to feast upon the stars.
Anna Pavlova appears courtesy of lorivintage55stock @ deviantart
2 hours ago