PERNI'CIOUS, adjective [Latin perniciosus, from pernicies; perneco, to kill; per and nex, necis, death.] 1. Destructive; having the quality of killing, destroying or injuring; very injurious or mischievous. Food, drink or air may be pernicious to life or health. 2. Destructive; tending to injure or destroy. Evil examples are pernicious to morals. Intemperance is a pernicious vice. 3. [Latin pernix.] Quick. [Not used.]
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI