一斉

一斉

"Simultaneously" or "all at once."

Here, '一斉に' means 'simultaneously' or 'at the same time,' describing an action performed by many individuals all together.

観客は一斉に拍手をした。

The audience clapped all at once.

In this sentence, '一斉に' is used to indicate that the action of leaving the classroom occurred simultaneously by all the children.

子供たちは一斉に教室を飛び出した。

The children dashed out of the classroom all at once.

Here, '一斉に' is used to illustrate that all the lights were activated at the same moment, emphasizing the simultaneous nature of the event.

店内の電灯が一斉に点いた。

The lights inside the shop turned on all at once.