〔いっしょに〕all together;〔一体となって〕all in one body;〔同時に〕at once, simultaneously;〔異口同音に〕in unison, with one voice, unanimously
- 彼らは一斉に笑った
- They laughed all together.
- 選挙の開票は全国一斉に行われる
- Ballot counting will begin simultaneously [at the same time] throughout the country.
- ベルが鳴ると皆一斉に立ち上った
- The moment the bell rang, they all stood up at once.
- 人々は何か叫びながらこちらへ向かって一斉に走って来た
- The people ran toward(s) us in a body shouting something.
- 一斉に「ノー」と叫んだ
- They shouted “No!” 「with one voice [in chorus].