impair

¹ American  

[im-pair] / ɪmˈpɛər /

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.

   Antonyms:

   repair

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verb (used without object)

1. to grow or become worse; lessen.

noun

1. Archaic. impairment.

impair ² American  

[an-per] / ɛ̃ˈpɛr /

adjective

French.

1. noting any odd number, especially in roulette.

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impair British  

/ ɪmˈpɛə /

verb

1. (tr) to reduce or weaken in strength, quality, etc

   his hearing was impaired by an accident

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Related Words

See injure.

Other Word Forms

• impairable
  adjective
• impairer
  noun
• impairment
  noun
• nonimpairment
  noun
• preimpairment
  noun
• self-impairable
  adjective
• self-impairing
  adjective
• unimpairable
  adjective

Etymology

Origin of impair¹

First recorded in 1250–1300; Middle English empairen, empeiren “to make worse,” from Middle French empeirer, from em- im- ¹ + peirer “to make worse” (from Late Latin pējōrāre, verb derivative of Latin pējor “worse”; cf. pejoration)

Origin of impair²

First recorded in 1820–30; from French: literally, “odd,” from Latin impār “odd, unequal”; equivalent to im- ² ( def. ) + pair ² ( def. )

Explanation

If you make bad decisions in the morning after drinking coffee, you might conclude that caffeine tends to impair your judgment. When you impair something, you damage it or make it work poorly. The root of the verb impair traces back to the Latin word pejorare, meaning “to make worse,” and that’s still what happens if you impair something. Whether it’s communication, visibility, or your marriage prospects, if you impair it, you make it worse. The word can be used for situations that describe something that has deteriorated, such as “Snow continued to impair driving conditions.”

Example Sentences

They react when uncertainty becomes persistent enough to impair planning.

From MarketWatch • May 12, 2026

Southpaw Nakatani had wrestled back some control but was halted in his tracks when blood began to impair vision in his left eye following a clash of heads.

From BBC • May 2, 2026

“Inadequate nutrition, particularly vitamin A deficiency, can impair the lining of the digestive tract, predisposing birds to inflammation and secondary illness.”

From Los Angeles Times • Apr. 20, 2026

It could also be forced to start shutting down oil wells within weeks as it runs out of storage space, a costly and damaging prospect that could impair production for years to come.

From The Wall Street Journal • Apr. 17, 2026

In the earlier discussion, however, I was referring to things that impair our ability to solve problems.

From "Blink" by Malcolm Gladwell

Related Words

• blunt
• damage
• debilitate
• decrease
• destroy
• diminish
• hurt
• lessen
• mar
• prejudice
• reduce
• spoil
• tarnish
• undermine
• weaken
• worsen