atonce
adverbUK /ət ˈwʌns/
US /ət ˈwʌns/
Right now, without waiting.
Come here at once!
OTHER MEANINGS
2. All at the same time together.
The kids all shouted at once.
3. Used to introduce a surprising or contrasting point.
At once clever and kind, she impressed everyone.
4. Suddenly and without warning.
At once the lights went out.