defection
UK: dɪˈfɛkʃən | US: dɪˈfɛkʃən
n. the act of abandoning a duty, allegiance, or principle
n. (formal) desertion from an organization, country, or cause
Derived from Latin defectio ("failure, revolt"), combining de- (away) + facere (to make/do). The root fect (from facere) evolved into English words like "factory" (a place of making) and "effect" (result of doing). "Defection" originally implied a "failure to perform" but narrowed to mean "abandonment" in political/military contexts by the 16th century.
His defection to the rival team shocked the fans.
The spy's defection revealed classified information.
Historical records show defections were common during the civil war.
She justified her defection from the party as a moral necessity.
The general prevented mass defection by boosting troop morale.