[ per-nish-uhs ]
/ pərˈnɪʃ əs /


causing insidious harm or ruin; ruinous; injurious; hurtful: pernicious teachings; a pernicious lie.
deadly; fatal: a pernicious disease.
Obsolete. evil; wicked.

Nearby words

  1. permutation,
  2. permutation group,
  3. permute,
  4. pernambuco,
  5. pernancy,
  6. pernicious anaemia,
  7. pernicious anemia,
  8. pernicious vomiting,
  9. perniciously,
  10. pernickety

Origin of pernicious

1515–25; < Latin perniciōsus ruinous, equivalent to pernici(ēs) ruin (per- per- + -nici-, combining form of nex death, murder (stem nec-) + -iēs noun suffix) + -ōsus -ous

Related formsper·ni·cious·ly, adverbper·ni·cious·ness, nounun·per·ni·cious, adjectiveun·per·ni·cious·ly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for pernicious

British Dictionary definitions for pernicious


/ (pəˈnɪʃəs) /


wicked or maliciouspernicious lies
causing grave harm; deadly
Derived Formsperniciously, adverbperniciousness, noun

Word Origin for pernicious

C16: from Latin perniciōsus, from perniciēs ruin, from per- (intensive) + nex death

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for pernicious



early 15c., from Middle French pernicios (13c., Modern French pernicieux) and directly from Latin perniciosus "destructive," from pernicies "destruction, death, ruin," from per- "completely" (see per) + necis "violent death, murder," related to necare "to kill," nocere "to hurt, injure, harm," noxa "harm, injury" (see noxious). Related: Perniciously; perniciousness.

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for pernicious


[ pər-nĭshəs ]


Tending to cause death or serious injury; deadly.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.