Definition of "at once" [at once]

• In one group; together. (adverb)
• At the same time; simultaneously. (adverb)
• Immediately; now; right away. (adverb)

Wiktionary.org : Text is available under the Creative Commons Attribution-ShareAlike License

• "At about the same time the ducal House of Pomerania was nearing extinction, so that all at once the state ruled by the Hohenzollerns seemed to approach a great extension of its territories."
• "Pressed in the Commons by Labour's deputy leader, Harriet Harman, to accede to a public inquiry, Clegg said: "If there are wider issues that need to be looked at once the police investigation is complete, of course we can return to them.""
• "Bobby Baldwin was dressed in gray trousers and a gray Lacoste tennis shirt, at once sporting and sober, to suit his image."