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verb (used with object)
  1. to make or cause to become worse; diminish in ability, value, excellence, etc.; weaken or damage: to impair one's health; to impair negotiations.
verb (used without object)
  1. to grow or become worse; lessen.
  1. Archaic. impairment.

Origin of impair1

1250–1300; Middle English empairen, empeiren to make worse < Middle French empeirer, equivalent to em- im-1 + peirer to make worse < Late Latin pējōrāre, equivalent to Latin pējōr-, stem of pējor worse + -ā- thematic vowel + -re infinitive suffix; cf. pejorative
Related formsim·pair·a·ble, adjectiveim·pair·er, nounim·pair·ment, nounnon·im·pair·ment, nounpre·im·pair·ment, nounself-im·pair·a·ble, adjectiveself-im·pair·ing, adjectiveun·im·pair·a·ble, adjective


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1. See injure.


1. repair.


adjective French.
  1. noting any odd number, especially in roulette.
Compare pair.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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British Dictionary definitions for impair


  1. (tr) to reduce or weaken in strength, quality, etchis hearing was impaired by an accident
Derived Formsimpairable, adjectiveimpairer, nounimpairment, noun

Word Origin

C14: from Old French empeirer to make worse, from Late Latin pējorāre, from Latin pejor worse; see pejorative
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 impair


late 14c., earlier ampayre, apeyre (c.1300), from Old French empeirier (Modern French empirer), from Vulgar Latin *impeiorare "make worse," from assimilated form of in- "into, in" (see in- (2)) + Late Latin peiorare "make worse" (see pejorative). In reference to driving under the influence of alcohol, first recorded 1951 in Canadian English. Related: Impaired; impairing.

Online Etymology Dictionary, © 2010 Douglas Harper