"a lord-master, a protector," c. 1300, from Old French patron "patron, protector, patron saint" (12c.) and directly from Medieval Latin patronus "patron saint, bestower of a benefice, lord, master, model, pattern," from Latin patronus "defender, protector, former master (of a freed slave); advocate," from pater (genitive patris) "father" (see father (n.)). Meaning "one who advances the cause" (of an artist, institution, etc.), usually by the person's wealth and power, is attested from late 14c.; "commonly a wretch who supports with insolence, and is paid with flattery" [Johnson]. Commercial sense of "regular customer" first recorded c. 1600. Patron saint (1717) originally was simply patron (late 14c.).