per (prep.)

"by, for," mid-13c., from Old French par, per, from Latin per (see per). It figures in some French phrases borrowed into English and in the formation of some words (parboil, pardon, parvenu). In some older borrowings from French it has been re-Latinized to per- (perceive, perfect, perform, pertain).

French, from Latin per excellentiam "by the way of excellence." French par "by, through, by way of, by means of" is from Latin per (see per). For second element, see excellence.