{adv. phr.} 1. Without delay; right now or right then; immediately. * /Put a burning match next to a piece of paper and it will begin burning at once./ * /Mother called the children to lunch, and Paul came at once, but Brenda stayed in the sand pile a little longer./ Syn.: RIGHT AWAY or RIGHT OFF. Compare: ALL AT ONCE(2).
AT ONCE
Meaning of AT ONCE in English
Slang English vocab. Английский сленговый словарь. 2012