'Defect' is Latin for 'undone' — from 'facere' (to do). Kin to 'affect,' 'effect,' and 'perfect.'
A shortcoming, imperfection, or lack (noun); to abandon one's country, cause, or allegiance in favor of an opposing one (verb).
From Latin 'defectus,' the past participle of 'dēficere,' meaning 'to fail, to desert, to be wanting,' composed of 'dē-' (away, down from) and 'facere' (to do, to make). The literal sense is 'undone' or 'unmade' — something that has failed in its making. The noun sense of 'flaw' appeared first in English (15th century); the verb sense of 'to desert to the other side' developed in the late 16th century from the Latin sense of 'failing' in one's allegiance
During the Cold War, 'to defect' became strongly associated with espionage and political asylum. Famous defectors include Rudolf Nureyev (ballet dancer, USSR to the West, 1961) and Kim Philby (British spy, to the USSR, 1963). The word's Latin meaning — 'to fail in one's duty' — captures