reaction definition, reaction meaning | English dictionary

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reaction

  

      n  
1    a response to some foregoing action or stimulus  
2    the reciprocal action of two things acting together  
3    opposition to change, esp. political change, or a desire to return to a former condition or system  
4    a response indicating a person's feelings or emotional attitude  
5      (Med)  
a    any effect produced by the action of a drug, esp. an adverse effect  
   Compare       side effect  
b    any effect produced by a substance (allergen) to which a person is allergic  
6    the simultaneous equal and opposite force that acts on a body whenever it exerts a force on another body  
7       short for       chemical reaction       nuclear reaction  
8      (Stock Exchange)   a sharp fall in price interrupting a general rise  
  reactional      adj  
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  


chain reaction  
      n  
1    a process in which a neutron colliding with an atomic nucleus causes fission and the ejection of one or more other neutrons, which induce other nuclei to split  
2    a chemical reaction in which the product of one step is a reactant in the following step  
3    a series of rapidly occurring events, each of which precipitates the next  
chemical reaction  
      n   a process that involves changes in the structure and energy content of atoms, molecules, or ions but not their nuclei  
   Compare       nuclear reaction  
dark reaction  
      n     (Botany)   the stage of photosynthesis involving the reduction of carbon dioxide and the dissociation of water, using chemical energy stored in ATP: does not require the presence of light  
   Compare       light reaction  
Diels-Alder reaction  
      n     (Chem)   a type of chemical reaction in which one organic compound containing conjugated double bonds adds to another containing an ethylenic bond to form a product containing a ring  
     (C20: named after Otto Diels (1876--1954) and Kurt Alder (1902--58), German chemists)  
gut reaction  
      n   a reaction to a situation derived from a person's instinct and experience  
heat of reaction  
      n     (Chem)   the heat evolved or absorbed when one mole of a product is formed at constant pressure  
insulin reaction   , shock  
      n   the condition in a diabetic resulting from an overdose of insulin, causing a sharp drop in the blood sugar level with tremor, profuse sweating, and convulsions  
   See also       hyperinsulinism  
light reaction  
      n     (Botany)   the stage of photosynthesis during which light energy is absorbed by chlorophyll and transformed into chemical energy stored in ATP  
   Compare       dark reaction  
nuclear reaction  
      n   a process in which the structure and energy content of an atomic nucleus is changed by interaction with another nucleus or particle  
reaction chamber  
      n     (Engineering)   the chamber in a rocket engine in which the reaction or combustion of fuel occurs  
reaction engine   , motor  
      n   an engine, such as a jet or rocket engine, that ejects gas at high velocity and develops its thrust from the ensuing reaction  
reaction formation  
      n     (Psychoanal)   a defence mechanism by which a person at a conscious level condemns a repressed wish: thus, a latent homosexual may denounce homosexuality  
reaction time  
      n     (Physiol)      another name for       latent time  
reaction turbine  
      n   a turbine in which the working fluid is accelerated by expansion in both the static nozzles and the rotor blades. Torque is produced by the momentum changes in the rotor and by reaction from fluid accelerating out of the rotor  
   Compare       impulse turbine  
thermonuclear reaction  
      n   a nuclear fusion reaction occurring at a very high temperature: responsible for the energy produced in the sun, nuclear weapons, and fusion reactors  
   See       nuclear fusion       hydrogen bomb  
English Collins Dictionary - English Definition & Thesaurus  
Collins
Wassermann test   , reaction            (German)  
      n     (Med)   a diagnostic test for syphilis  
   See       complement fixation test  
     (C20: named after August von Wassermann (1866--1925), German bacteriologist)  


chain reaction  
      n  
1    a process in which a neutron colliding with an atomic nucleus causes fission and the ejection of one or more other neutrons, which induce other nuclei to split  
2    a chemical reaction in which the product of one step is a reactant in the following step  
3    a series of rapidly occurring events, each of which precipitates the next  
chemical reaction  
      n   a process that involves changes in the structure and energy content of atoms, molecules, or ions but not their nuclei  
   Compare       nuclear reaction  
dark reaction  
      n     (Botany)   the stage of photosynthesis involving the reduction of carbon dioxide and the dissociation of water, using chemical energy stored in ATP: does not require the presence of light  
   Compare       light reaction  
Diels-Alder reaction  
      n     (Chem)   a type of chemical reaction in which one organic compound containing conjugated double bonds adds to another containing an ethylenic bond to form a product containing a ring  
     (C20: named after Otto Diels (1876--1954) and Kurt Alder (1902--58), German chemists)  
gut reaction  
      n   a reaction to a situation derived from a person's instinct and experience  
heat of reaction  
      n     (Chem)   the heat evolved or absorbed when one mole of a product is formed at constant pressure  
insulin reaction   , shock  
      n   the condition in a diabetic resulting from an overdose of insulin, causing a sharp drop in the blood sugar level with tremor, profuse sweating, and convulsions  
   See also       hyperinsulinism  
light reaction  
      n     (Botany)   the stage of photosynthesis during which light energy is absorbed by chlorophyll and transformed into chemical energy stored in ATP  
   Compare       dark reaction  
nuclear reaction  
      n   a process in which the structure and energy content of an atomic nucleus is changed by interaction with another nucleus or particle  
reaction         
      n  
1    a response to some foregoing action or stimulus  
2    the reciprocal action of two things acting together  
3    opposition to change, esp. political change, or a desire to return to a former condition or system  
4    a response indicating a person's feelings or emotional attitude  
5      (Med)  
a    any effect produced by the action of a drug, esp. an adverse effect  
   Compare       side effect  
b    any effect produced by a substance (allergen) to which a person is allergic  
6    the simultaneous equal and opposite force that acts on a body whenever it exerts a force on another body  
7       short for       chemical reaction       nuclear reaction  
8      (Stock Exchange)   a sharp fall in price interrupting a general rise  
  reactional      adj  
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 chamber  
      n     (Engineering)   the chamber in a rocket engine in which the reaction or combustion of fuel occurs  
reaction engine   , motor  
      n   an engine, such as a jet or rocket engine, that ejects gas at high velocity and develops its thrust from the ensuing reaction  
reaction formation  
      n     (Psychoanal)   a defence mechanism by which a person at a conscious level condemns a repressed wish: thus, a latent homosexual may denounce homosexuality  
reaction time  
      n     (Physiol)      another name for       latent time  
reaction turbine  
      n   a turbine in which the working fluid is accelerated by expansion in both the static nozzles and the rotor blades. Torque is produced by the momentum changes in the rotor and by reaction from fluid accelerating out of the rotor  
   Compare       impulse turbine  
thermonuclear reaction  
      n   a nuclear fusion reaction occurring at a very high temperature: responsible for the energy produced in the sun, nuclear weapons, and fusion reactors  
   See       nuclear fusion       hydrogen bomb  

English Collins Dictionary - English Definition & Thesaurus  

Collins

reaction

  
1    acknowledgment, answer, feedback, reply, response  
2    compensation, counteraction, counterbalance, counterpoise, recoil  
3    conservatism, counter-revolution, obscurantism, the right  

English Collins Dictionary - English synonyms & Thesaurus  

Collaborative Dictionary     English Definition
n.
The practice of monitoring the effects of medical drugs, especially in order to identify and evaluate previously unreported adverse reactions
[Med.] Ex: In his job as a pharmacovigilance officer, Andrew develops diagnostic tools to improve drug safety
exp.
it's said for determining someone to calm down, be patient, control his/her reactions
n.
Patient that has lost reactivity , reactions to stimulations, reflexes (Areflexia) = Dead or Comatous
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