Per*ni"cious (?), a. [L. pernix, -icis.] Quick; swift (to burn). [R.] Milton.

Per*ni"cious, a. [L. perniciosus, from pernicies destruction, from pernecare to kill or slay outright; per + necare to kill, slay: cf. F. pernicieux. Cf. Nuisance, Necromancy.] Having the quality of injuring or killing; destructive; very mischievous; baleful; malicious; wicked.

Let this pernicious hour
Stand aye accursed in the calendar.

Pernicious to his health.

Syn. -- Destructive; ruinous; deadly; noxious; injurious; baneful; deleterious; hurtful; mischievous.

-- Per*ni"cious*ly, adv., -- Per*ni"cious*ness, n.

• causing death or injury; deadly
  
• causing much harm; destructive