re·ac·tion (r - k sh n)n.1. a. A response to a stimulus. b. The state resulting from such a response. 2. A reverse or opposing action. 3. a. A tendency to revert to a former state. b. Opposition to progress or liberalism; extreme conservatism. 4. Chemistry A change or transformation in which a substance decomposes, combines with other substances, or interchanges constituents with other substances. 5. Physics A nuclear reaction. 6. Physics An equal and opposite force exerted by a body against a force acting upon it. 7. The response of cells or tissues to an antigen, as in a test for immunization. |
reaction Noun 1. a physical or emotional response to a stimulus 2. any action resisting another 3. opposition to change 4. Med any effect produced by a drug or by a substance (allergen) to which a person is allergic 5. Chem a process that involves changes in the structure and energy content of atoms, molecules, or ions 6. the equal and opposite force that acts on a body whenever it exerts a force on another body 7. reactions someone's ability to act in response to something that happens USAGE: Reaction is used to refer both to an instant response (her reaction was one of amazement) and to a considered response in the form of a statement (the Minister gave his reaction to the court's decision). Some people think this second use is incorrect.
reaction (r-kshn)1. A rearrangement of the atoms or molecules of two or more substances that come into contact with each other, resulting in the formation of one or more new substances. Chemical reactions are caused by electrons of one substance interacting with those of another. The reaction of an acid with a base, for example, results in the creation of a salt and water. Some, but not all, reactions can be reversed. 3. An action that results directly from or counteracts another action, especially the change in a body's motion as a result of a force applied to it. Some reactions counteract forces and are not readily apparent. When an object rests on a surface, such as a table, for example, the downward force it applies to the surface is counteracted by an equal but upwards force, or reaction, applied by the surface. See more at Newton's laws of motion. 4. A response to a stimulus, such as a reflex. 5. The response of cells or tissues to an antigen, as in a test for immunization. |
ThesaurusLegend: Synonyms Related Words Antonyms | Noun | 1. |  reaction - (chemistry) a process in which one or more substances are changed into others; "there was a chemical reaction of the lime with the ground water"chemical science, chemistry - the science of matter; the branch of the natural sciences dealing with the composition of substances and their properties and reactions chain reaction - a series of chemical reactions in which the product of one is a reactant in the next elimination reaction - a chemical reaction in which a molecule decomposes to two different molecules hydrolysis - a chemical reaction in which water reacts with a compound to produce other compounds; involves the splitting of a bond and the addition of the hydrogen cation and the hydroxide anion from the water oxidation, oxidisation, oxidization - the process of oxidizing; the addition of oxygen to a compound with a loss of electrons; always occurs accompanied by reduction reducing, reduction - any process in which electrons are added to an atom or ion (as by removing oxygen or adding hydrogen); always occurs accompanied by oxidation of the reducing agent saponification - a chemical reaction in which an ester is heated with an alkali (especially the alkaline hydrolysis of a fat or oil to make soap) | | 2. | reaction - an idea evoked by some experience; "his reaction to the news was to start planning what to do"idea, thought - the content of cognition; the main thing you are thinking about; "it was not a good idea"; "the thought never entered my mind" | | 3. | reaction - a bodily process occurring due to the effect of some antecedent stimulus or agent; "a bad reaction to the medicine"; "his responses have slowed with age"automatism - any reaction that occurs automatically without conscious thought or reflection (especially the undirected behavior seen in psychomotor epilepsy) rebound - a reaction to a crisis or setback or frustration; "he is still on the rebound from his wife's death" overreaction - an excessive reaction; a reaction with inappropriate emotional behavior tropism - an involuntary orienting response; positive or negative reaction to a stimulus source taxis - a locomotor response toward or away from an external stimulus by a motile (and usually simple) organism kinesis - a movement that is a response to a stimulus but is not oriented with respect to the source of stimulation passing, passage - a bodily reaction of changing from one place or stage to another; "the passage of air from the lungs"; "the passing of flatus" answer - a nonverbal reaction; "his answer to any problem was to get drunk"; "their answer was to sue me" transfusion reaction - reaction of the body to a transfusion of blood that is not compatible with its own blood; an adverse reaction can range from fever and hives to renal failure and shock and death | | 4. | reaction - (mechanics) the equal and opposite force that is produced when any force is applied to a body; "every action has an equal and opposite reaction"mechanics - the branch of physics concerned with the motion of bodies in a frame of reference force - (physics) the influence that produces a change in a physical quantity; "force equals mass times acceleration" | | 5. |  reaction - a response that reveals a person's feelings or attitude; "he was pleased by the audience's reaction to his performance"; "John feared his mother's reaction when she saw the broken lamp"response - a result; "this situation developed in response to events in Africa" | | 6. | reaction - extreme conservatism in political or social matters; "the forces of reaction carried the election"conservatism, conservativism - a political or theological orientation advocating the preservation of the best in society and opposing radical changes | | 7. | reaction - doing something in opposition to another way of doing it that you don't like; "his style of painting was a reaction against cubism"opposition, resistance - the action of opposing something that you disapprove or disagree with; "he encountered a general feeling of resistance from many citizens"; "despite opposition from the newspapers he went ahead" backlash - an adverse reaction to some political or social occurrence; "there was a backlash of intolerance" |
reaction noun 3. conservatism, the right, counter-revolution, obscurantism USAGE Some people say that reaction should always refer to an instant response to something (as in his reaction was one of amazement), and that this word should not be used to refer to a considered response given in the form of a statement (as in the Minister gave his reaction to the court's decision). Use response instead.  Translations reaction [riːˈækʃən] n → reacción f
 reaction [riːˈækʃən] react n → réaction f
 reaction [riːˈækʃən] react n → Reaktion f; reactions react npl (reflexes) → Reaktionen pl;
 reaction [riːˈækʃən] n → reazione f
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