defection (n.)

1540s, "action of failing," especially in performance of duty or obligation; 1550s, "action of deserting or abandoning a party, leader, cause, etc." (in early use often of faith); from Latin defectionem (nominative defectio) "desertion, revolt, failure," noun of action from past-participle stem of 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").