verb im·pair \im-ˈper\

Definition of impair

  1. transitive verb
  2. :  to diminish in function, ability, or quality :  to weaken or make worse It has been known for nearly 100 years that memory is impaired by bilateral damage to either of two brain regions … — Larry R. Squire The use of drugs further complicates the situation of these families and sometimes impairs their ability to raise children. — Ellen L. Bassuk … the prospect of generating normal profitability is impaired by excessive debt service. — John Nozell The physician also checks for signs of endometriosis, a condition in which the cells that normally compose the uterine lining grow outside the uterus, sometimes impairing fertility. — Martha Southgate


noun … the overwhelming majority of hookups involved alcohol use—an impairer of sexual judgment if ever there was one … — Tiffany Sharples


play \im-ˈper-mənt\ noun Persons with hearing impairments can now get information about local parks and their facilities by calling the recently installed TDD phone numbers within the Parks Department. — Maryland Magazine

Examples of impair in a sentence

  1. Smoking can impair your health.

  2. Drinking impairs a person's ability to think clearly.

  3. His memory was so impaired by age that he often forgot where he was.

Origin and Etymology of impair

Middle English empeiren, from Anglo-French empeirer, from Vulgar Latin *impejorare, from Latin in- + Late Latin pejorare to make worse — more at pejorative

First Known Use: 14th century

Synonym Discussion of impair

injure, harm, hurt, damage, impair, mar mean to affect injuriously. injure implies the inflicting of anything detrimental to one's looks, comfort, health, or success. badly injured in an accident harm often stresses the inflicting of pain, suffering, or loss. careful not to harm the animals hurt implies inflicting a wound to the body or to the feelings. hurt by their callous remarks damage suggests injury that lowers value or impairs usefulness. a table damaged in shipping impair suggests a making less complete or efficient by deterioration or diminution. years of smoking had impaired his health mar applies to injury that spoils perfection (as of a surface) or causes disfigurement. the text is marred by many typos

IMPAIR Defined for Kids


verb im·pair \im-ˈper\

Definition of impair for Students




  1. :  to make less (as in quantity, value, or strength) or worse :  damage Smoking can impair your health.

Medical Dictionary


transitive verb im·pair \im-ˈpa(ə)r, -ˈpe(ə)r\

Medical Definition of impair

  1. :  to damage or make worse by or as if by diminishing in some material respect his health was impaired by overwork


\-ˈpa(ə)r-mənt\play noun

Law Dictionary


transitive verb im·pair \im-ˈper\

Legal Definition of impair

  1. 1 :  to damage or make worse by or as if by diminishing impaired health

  2. 2 :  to diminish the value of (property or property rights); specifically :  to diminish the value of (legal contractual obligations) to the point that a party loses the benefit of the contract or the contract otherwise becomes invalid a law impairing a state's own obligations was entitled to less deference — Gerald Gunther — see also contract clause



Seen and Heard

What made you want to look up impair? Please tell us where you read or heard it (including the quote, if possible).


to cast off or become cast off

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