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Adverb: at once
  1. Without delay or hesitation; with no time intervening
    "he answered at once";
    - immediately, instantly, straightaway, straight off, directly, now, right away, forthwith, like a shot [informal], right off the bat [N. Amer, informal], instantaneously, outright, in a flash, tout de suite
  2. Simultaneously
    "he took three cookies at once";
    - at a time, at one time