Impair, v. t. [imp & p. p. Impaired; p. pr. & vb. n. Impairing.]
[Written also empair.] Etym: [OE. empeiren, enpeiren, OF. empeirier, empirier, F. empirer, LL. impejorare; L. pref. im- in + pejorare to make worse, fr. pejor worse. Cf. Appair.]
To make worse; to diminish in quantity, value, excellence, or strength; to deteriorate; as, to impair health, character, the mind, value. Time sensibly all things impairs. Roscommon. In years he seemed, but not impaired by years. Pope.
Syn. -- To diminish; decrease; injure; weaken; enfeeble; debilitate; reduce; debase; deteriorate.
3 other Webster entries under this spelling
Impair, v. t.
To grow worse; to deteriorate. Milton.
Impair, a.
Not fit or appropriate. [Obs.]
Impair, n.
Diminution; injury. [Obs.]
Shades of meaning
Fernald lists impair only as an antonym, under amend.
He lists it without comment; the entries above explain its neighbors.