(intransitive) To act in response. / (transitive, now rare) To act or perform a second time; to do over again; to reenact.

(Internet) An emoji used to express a reaction to a post on social media.

simple past tense and past participle of react

present participle of react

Third-person singular simple present indicative form of react

plural of react

(physics) A nuclear reaction in which particles produced by the fission of one atom trigger fissions of other atoms. / (figuratively) A series of events, each one causing or influencing the next.

plural of Suzuki reaction

(chemistry) The organic reaction of an aryl- or vinyl-boronic acid with an aryl- or vinyl-halide or pseudohalide, such as triflates, catalyzed by a palladium(0) complex, widely used to synthesize polyolefins, styrenes, and substituted biphenyls.

plural of reactionary