noun
plural -tions
the way someone acts or feels in response to something that happens, is said, etc. [count]
an action or attitude that shows disagreement with or disapproval of someone or something [count]
usually singular; often + against
reactions [plural] :the ability to act and move quickly in order to avoid sudden danger
medical :an occurrence in which your body is affected by a drug, food, etc., in usually a bad way [count]
a chemistry :a chemical change that occurs when two or more substances combine to form a new substance [count]
[count, noncount] physics :a process in which the nucleus of an atom is changed by being split apart or joined with the nucleus of another atom - called also nuclear reaction, - see also chain reaction
[count, noncount] physics :a physical force that opposes the action of an equal and opposite force
[noncount] formal :a strong tendency or desire to oppose new political or social ideas
