de·fect 
(dēfĕkt′, dĭ-fĕkt)
(dēfĕkt′, dĭ-fĕkt)n.
An imperfection or lack that causes inadequacy or failure; a shortcoming or deficiency. See Synonyms at blemish.
intr.v. (dĭ-fĕkt) de·fect·ed, de·fect·ing, de·fects
1. To disown allegiance to one's country and take up residence in another: a Soviet citizen who defected to Israel.
2. To abandon a position or association, often to join an opposing group: defected from the party over the issue of free trade.
[Middle English, from Latin dēfectus, failure, want, from past participle of dēficere, to desert, be wanting : dē-, de- + facere, to do; see dhē- in the Appendix of Indo-European roots.]
de·fection n.
de·fector n.