Plain form
react

Third-person singular
reacts

Past tense
reacted

Past participle
reacted

Present participle
reacting

(intransitive) If you react to a person or event, you do something because of the person or event.
When someone shouts at you, you usually react by shouting back.
(intransitive) If you react to a medicine or other substance, something happens in your body because of it.
She reacts badly to asprin. Her skin becomes red all over her body.
(intransitive) When two or more chemicals react, they combine to form new chemical compounds.
Acids and alkalis normally react to form salt and water.

Verb