<p><strong>Conjunction</strong></p><ul><li>up to the time that or when; till:<ul><li>He read until his guests arrived.</li></ul></li><li>before (usually used in negative constructions):<ul><li>They did not come until the meeting was half over.</li></ul></li></ul><p><strong>Preposition</strong></p><ul><li>onward to or till (a specified time or occurrence):<ul><li>She worked until 6 p.m.</li></ul></li><li>before (usually used in negative constructions):<ul><li>He did not go until night.</li></ul></li><li>Scot. and North England:<ul><li>to; unto.</li></ul></li></ul>