verb (used with object)
to or perform again.
verb (used without object)
to act in response to an agent or influence:
How did the audience react to the speech?
to act reciprocally upon each other, as two things.
to act in a reverse direction or manner, especially so as to return to a prior condition.
to act in opposition, as against some force.
to respond to a stimulus in a particular manner:
reacting to a shock by jumping; to react to the word “coward” with anger.
to undergo a chemical .
(intransitive; foll by to, upon etc) (of a person or thing) to act in response to another person, a stimulus, etc, or (of two people or things) to act together in a certain way
(intransitive) foll by against. to act in an opposing or contrary manner
(intransitive) (physics) to exert an equal force in the opposite direction to an acting force
(chem) to undergo or cause to undergo a chemical reaction
(transitive) to act or perform again
1640s, “to exert, as a thing acted upon, an opposite action upon the agent,” from re- + act (v.). Chemical sense is from 1944. Related: Reacted; reacting (1610s). For sense development, see reaction. Meaning “perform again” (often re-act) is from 1650s.
react re·act (rē-ākt’)
v. re·act·ed, re·act·ing, re·acts
[ree-ak-shuh n] /riˈæk ʃən/ noun 1. a reverse movement or tendency; an action in a reverse direction or manner. 2. movement in the direction of political conservatism or extreme rightism. 3. action in response to some influence, event, etc.: the nation’s reaction to the president’s speech. 4. Physiology. action in response to a stimulus, as […]
[ree-ak-shuh-ner-ee] /riˈæk ʃəˌnɛr i/ adjective 1. of, pertaining to, marked by, or favoring , especially extreme conservatism or rightism in politics; opposing political or social change. noun, plural reactionaries. 2. a reactionary person. /rɪˈækʃənərɪ; -ʃənrɪ/ adjective 1. of, relating to, or characterized by reaction, esp against radical political or social change noun (pl) -aries, -ists […]
noun, Aeronautics, Rocketry. 1. an engine that produces power as a reaction to the momentum given to gases ejected from it, as a rocket or jet engine. noun 1. an engine, such as a jet or rocket engine, that ejects gas at high velocity and develops its thrust from the ensuing reaction
- Reaction chamber
noun 1. (engineering) the chamber in a rocket engine in which the reaction or combustion of fuel occurs