react

verb

1. show a response or a reaction to something

   verb.cognition

   Synonyms respond

   Source: WordNet 3.0

2. act against or in opposition to

   verb.social

   Examples

   She reacts negatively to everything I say.

   Synonyms oppose

   Source: WordNet 3.0

3. undergo a chemical reaction; react with another substance under certain conditions

   verb.change

   Examples

   The hydrogen and the oxygen react.

   Source: WordNet 3.0

4. To act or perform a second time; to do over again; as, to <i>react</i> a play; the same scenes were <i>reacted</i> at Rome.

   verb

   Source: webster1913

5. To return an impulse or impression; to resist the action of another body by an opposite force; as, every body <i>reacts</i> on the body that impels it from its natural state.

   verb

   Source: webster1913