Definition of: once

(wuns) adverb
1. One time, without repetition.
2. During some past time.
3. At any time; ever; also, at some future time.
—adjective Former; formerly existing; quondam.
—conj. As soon as; whenever.
—noun One time.
—all at once All of a sudden.
—at once.
1. Simultaneously.
2. Immediately.
—once for all Finally.
—once in a while Occasionally.
—this once On this occasion only. [ME ones, OE anes, genitive of an one]