I. preposition
Etymology: Middle English, from un- (probably from Old Norse *und up to; akin to Old Norse unz up to, until, Old High German unt, Old English ende end) + til, till till
Date: 13th century
to ,
2. — used as a function word to indicate continuance (as of an action or condition) to a specified time
II. conjunction
Date: 14th century
up to the time that ; up to such time as