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early 14c., "to fulfill, carry out," from Old French compli, past participle of complir "to accomplish, fulfill, carry out," from Vulgar Latin *complire, from Latin complere "to fill up" (see complete (adj.)). Meaning influenced by ply (v.2). Sense of "to consent" began c.1600 and might have been a reintroduction from Italian, where complire had come to mean "satisfy by 'filling up' the forms of courtesy."