A counterattack or counteroffensive; to strike back against an attack (used literally in military contexts or figuratively).
敵の反撃を受けて我軍は撤退した。
Our forces retreated after receiving a counterattack from the enemy.
選手は相手の攻撃に対してすぐに反撃した。
The player immediately countered the opponent's attack.
価格競争の反撃として新たな割引を発表した。
As a countermeasure in the price war, they announced a new discount.