unto (prep.)
mid-13c., perhaps a modification of until, with southern to in place of northern equivalent till. Or perhaps a contraction of native *und to, formed on the model of until from Old English *un- "up to, as far as," cognate of the first element in until. "Very rare in standard writers of the 18th c.," according to OED, and since then chiefly in dignified, archaic, or Biblical styles.