undergo a chemical reaction; react with another substance under certain conditions
The hydrogen and the oxygen react.
source: WordNet 3.0
To act or perform a second time; to do over again; as, to react a play; the same scenes were reacted at Rome.
source: Webster 1913
To return an impulse or impression; to resist the action of another body by an opposite force; as, every body reacts on the body that impels it from its natural state.
