► 名詞一斉  [いっせい]    
meaning:  simultaneous  rank: 2☆ 
彼等は
敵の
複数の
都市に一斉
攻撃を
行った ⇨ They executed simultaneous attacks on multiple cities of the enemy
☆ 
観衆は皆一斉に
拍手をした ⇨ The audience started applauding all at once
More examples:- 彼女の「御飯よ」の掛け声で犬達が一斉に駆け寄って来た ⇨ When she called “meal”, the dogs came running all at once
 - 暴力団の一斉摘発 ⇨ Coordinated mass arrests of mafias
 - 鳥が一斉に飛び立った ⇨ All the birds took off together
 - 兵隊達が一斉に射撃した ⇨ The soldiers fired all at once