Usage Note: Till and until are generally interchangeable in both writing and speech, though as the first word in a sentence until is usually preferred: Until you get that paper written, don't even think about going to the movies. · Till is actually the older word, with until having been formed by the addition to it of the prefix un-, meaning "up to." In the 1700s, the spelling 'till became fashionable, as if till were a shortened form of until. Although 'till is now nonstandard, 'til is sometimes used in this way and is considered acceptable, though it is etymologically incorrect.