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