Pernicious
PERNI'CIOUS,
a. [L. 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. [L. pernix.] Quick. [Not used.]