Meaning

adjective contaminated with infecting organisms; ; - Jane Austen

adjective likely to spread and cause an epidemic disease; - Jonathan Swift

adjective tending to corrupt or pervert

originMid 15th century, in sense “mischievous, pernicious”, from Latin pestiferus (“bearing plague”), from pestifer, from pestis (“plague”) + ferre (“carry”) (see infer). By surface analysis, pest + -i- (“bearing, carrying”) + -ferous.

Etymology from Wiktionary, CC BY-SA 3.0