defect

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The lack of something necessary or desirable for completion or perfection; a deficiency: a visual defect.
2. n. An imperfection that causes inadequacy or failure; a shortcoming. See Synonyms at blemish.
3. v. To disown allegiance to one's country and take up residence in another: a Soviet citizen who defected to Israel.
4. v. To abandon a position or association, often to join an opposing group: defected from the party over the issue of free trade.

Century Dictionary and Cyclopedia

1. n. Want or lack of anything; especially, the lack of something which is essential to perfection or completeness; a fault; a blemish; an imperfection: as, a defect in timber; a defect in the organs of hearing or seeing; a defect of memory or judgment.
2. n. Synonyms Deficiency, lack, insufficiency, failure, error, flaw.
3. To be or become deficient; fail.
4. To desert; revolt.
5. To affect injuriously; hurt; impair; spoil.
6. Defective.

Wiktionary

1. n. A fault or malfunction.
2. v. intransitive To abandon or turn against; to cease or change one's loyalty.

GNU Webster's 1913

1. n. Want or absence of something necessary for completeness or perfection; deficiency; -- opposed to superfluity.
2. n. Failing; fault; imperfection, whether physical or moral; blemish.
3. v. obsolete To fail; to become deficient.
4. v. to abandon one country or faction, and join another.
5. v. rare, rare To injure; to damage.

WordNet 3.0

1. v. desert (a cause, a country or an army), often in order to join the opposing cause, country, or army
2. n. an imperfection in a bodily system
3. n. an imperfection in an object or machine
4. n. a mark or flaw that spoils the appearance of something (especially on a person's body)
5. n. a failing or deficiency