once synonyms, pronunciation, spelling and more from Free Dictionary. one - WordReference thesaurus: synonyms, discussion and more. All Free. once definition: 1. one single time: 2. at the same time: 3. used when something happens that does not usually…. adv. Define once more. Once in a lifetime definition at Dictionary.com, a free online dictionary with pronunciation, synonyms and translation. 4. Definition of once. At any time; ever: Once known, his face is never forgotten. One time only: once a day. 2. What does once mean? This is the British English definition of at once.View American English definition of at once.. Change your default dictionary to American English. One time only: once a day. OneLook Thesaurus and Reverse Dictionary 18,955,870 words in 1061 dictionaries indexed — Today's word is asio Reverse Dictionary Browse Dictionaries Help At one time in the past; formerly. 1. once more synonyms, once more pronunciation, once more translation, English dictionary definition of once more. At once definition at Dictionary.com, a free online dictionary with pronunciation, synonyms and translation. Look it up now! 1. once synonyms, once pronunciation, once translation, English dictionary definition of once. Look it up now! adv. 2. Another word for at once. Learn more. Define once. Synonyms: for the last time, finally, completely, for good More Synonyms of once and for all See full dictionary entry for once COBUILD Advanced English Dictionary . Search once it was done and thousands of other words in English definition and synonym dictionary from Reverso. ADVERB (3) 1. on one occasion; - Example: "once I ran into her" [syn: once, one time, in one case] 2. 3. Search Result for "once": Wordnet 3.0. Meaning of once. Definition and synonyms of at once from the online English dictionary from Macmillan Education.. Definitions/synonyms are immediately available for viewing, emailing, or downloading. Simply copy and paste a list with any delimeter. Look up multiple words quickly. Find more ways to say at once, along with related words, antonyms and example phrases at Thesaurus.com, the world's most trusted free thesaurus.