To act or perform a second time; to do over again; as, to react a play; the same scenes were reacted at Rome.
- To act in response to or under the influence of a stimulus or prompting: reacted strongly to the sarcastic tone of the memorandum.
- To act in opposition to a former condition or act: composers who reacted against romanticism.
- To act reciprocally or in return.
- Chemistry To undergo a reaction: Methane reacts with hydroxyl to produce formaldehyde.
- Chemistry To cause (a substance or substances) to undergo a reaction.