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)
2.
to grow or become worse; lessen.
–noun
3.
Archaic. impairment.
Origin: 1250–1300; ME empairen, empeiren to make worse < MF empeirer, equiv. to em-im-1+ peirer to make worse < LL pējōrāre, equiv. to L pējōr-, s. of pējor worse + -ā- thematic vowel + -re inf. suffix; cf. pejorative
c.1374, earlier ampayre, apeyre (1297), from O.Fr. empeirier, from V.L. *impejorare "make worse," from L. in- "into" + L.L. pejorare "make worse," from pejor "worse." In ref. to driving under the influence of alcohol, first recorded 1951 in Canadian Eng.
Main Entry: im·pair Pronunciation: im-'per Function: transitive verb 1: to damage or make worse by or as if by diminishing <impaired health> 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 impairing a state's own obligations was entitled to less deference —Gerald Gunther> —see also CONTRACT CLAUSE —im·pair·mentnoun
Main Entry: im·pair Pronunciation: im-'pa(&)r, -'pe(&)r Function: transitive verb : to damage or make worse by or as if by diminishing in somematerial respect impaired by overwork> —im·pair·ment/-'pa(&)r-m&nt/noun
[im-pair] 
