late 14c., "action of inducing (someone) to believe (something); argument to persuade, inducement," from Old French persuasion (14c.) and directly from Latin persuasionem (nominative persuasio) "a convincing, persuading," noun of action from past participle stem of persuadere "persuade, convince," from per "thoroughly, strongly" (see per) + suadere "to urge, persuade," from PIE root *swād- "sweet, pleasant" (see sweet (adj.)). Meaning "religious belief, creed" is from 1620s.
