Defect, n.
Etymology: [L. defectus, fr. deficere, defectum, to desert, fail, be wanting; de- + facere to make, do. See Fact, Feat, and cf. Deficit.]
1. Want or absence of something necessary for completeness or perfection; deficiency; -- opposed to superfluity. Errors have been corrected, and defects supplied. Davies.
2. Failing; fault; imperfection, whether physical or moral; blemish; as, a defect in the ear or eye; a defect in timber or iron; a defect of memory or judgment. Trust not yourself; but, your defects to know, Make use of every friend -- any every foe. Pope. Among boys little tenderness is shown to personal defects. Macaulay.
Syn. -- Deficiency; imperfection; blemish. See Fault.
2 other Webster entries under this spelling
Defect, v. i.
To fail; to become deficient. [Obs.] "Defected honor." Warner.
Defect, v. t.
To injure; to damage. "None can my life defect." [R.] Troubles of Q. Elizabeth (1639).
Shades of meaning
Fernald has no entry of its own for defect; he lists it under blemish.
Where he writes about it:
A defect is the want or lack of something; fault, primarily a failing, is something that fails of an apparent intent or disappoints a natural expectation; thus a sudden dislocation or displacement of geological strata is called a fault. — from blemish