Pernicious

Part of speech: adjective (a.)

Quick; swift (to burn). [R.] Milton.

Part of speech: adjective (a.)

Having the quality of injuring or killing; destructive; very mischievous; baleful; malicious; wicked. Let this pernicious hour Stand aye accursed in the calendar. Shak. Pernicious to his health. Prescott.

Synonyms: Destructive; ruinous; deadly; noxious; injurious; baneful; deleterious; hurtful; mischievous. Per*ni"cious*ly, adv., -- Per*ni"cious*ness, n.