until (prep.)

Middle English til, tille "(going) onward to and into; (extending) as far as; (in time) continuing up to;" from Old English til (Northumbrian) "to," and from Old Norse til "to, until," both from Proto-Germanic *tilan (source also of Danish til, Old Frisian til "to, till," Gothic tils "convenient," German Ziel "limit, end, goal").

A common preposition in Scandinavian, serving in the place of English to, probably originally the accusative case of a noun otherwise lost but preserved in Icelandic tili "scope," the noun used to express aim, direction, purpose (as in aldrtili "death," literally "end of life"). Also compare German Ziel "end, limit, point aimed at, goal," and till (v.).

As a conjunction, "until, to the time that or when," from late Old English.

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.