/riˈækt ||; rɪˈækt/verb[I] 1 react (to sth) (by doing sth) to do or say sth because of sth that has happened or been said 作出反应；回应: He reacted to the news by jumping up and down and shouting. 他一听到这消息就跳上跳下，大喊大叫。The players reacted angrily to the decision. 球员们对这个决定很生气。
2 react (to sth) to become ill after eating, breathing, etc a particular substance （吃或吸入某物后）觉得不舒服
3 react (with sth/together) (used about a chemical substance) to change after coming into contact with another substance （指化学物质）起化学作用
react against sb/sth to behave or talk in a way that shows that you do not like the influence of sb/sth (for example authority, your family, etc) 反对，反抗（当权者、家庭等）