1540s, "to disown, disinherit (children)," from Latin abdicatus, past participle of abdicare "to disown, disavow, reject" (specifically abdicare magistratu "renounce office"), literally "proclaim as not belonging to one," from ab "off, away from" (see ab-) + dicare "proclaim" (from PIE root *deik- "to show," also "pronounce solemnly," and see diction). Meaning "divest oneself of office, privilege, etc., before the term expires" is recorded by 1610s in English (it was in classical Latin). Related: Abdicated; abdicating.