Origin and history of defect

late 14c., defeten, diffaiten, "overcome (with sorrow or anger)," from Anglo-French defeter, from Old French desfait, past participle of desfaire "to undo," from Vulgar Latin *diffacere "undo, destroy," from Latin dis- "un-, not" (see dis-) + facere "to do, perform," from PIE root *dhe- "to set, put."

From early 15c. as "bring ruination, cause destruction" (now obsolete in this sense); from late 15c. as "frustrate, prevent the success of." Sense of "deprive of something expected, desired or striven for" is from 1530s. Meaning "overcome in a contest of any kind" is from 1560s. Related: Defeated; defeating. Compare defect, deficient.

"a seceder or deserter," 1660s, agent noun in Latin form from defect, or else from Latin defector "revolter," agent noun from deficere "to desert, revolt, fail," from de "down, away" (see de-) + combining form of facere "to do, make" (from PIE root *dhe- "to set, put"). Specifically of important persons who fled the Soviet-dominated countries to the West by 1953.