• WordNet 3.6
    • n 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"
    • n 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"
    • n reaction an idea evoked by some experience "his reaction to the news was to start planning what to do"
    • n reaction extreme conservatism in political or social matters "the forces of reaction carried the election"
    • n 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"
    • n 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"
    • n 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"
    • ***
Webster's Revised Unabridged Dictionary
  • Interesting fact: People with allergies can lower allergy reactions by laughing
    • Reaction (Psycophysics) A regular or characteristic response to a stimulation of the nerves.
    • Reaction An action by a person or people in response to an event. The reaction may be primarily mental (“ a reaction of surprise”) but is usually manifested by some activity.
    • Reaction (Med) An action induced by vital resistance to some other action; depression or exhaustion of vital force consequent on overexertion or overstimulation; heightened activity and overaction succeeding depression or shock.
    • Reaction Any action in resisting other action or force; counter tendency; movement in a contrary direction; reverse action.
    • Reaction (Politics) Backward tendency or movement after revolution, reform, or great progress in any direction. "The new king had, at the very moment at which his fame and fortune reached the highest point, predicted the coming reaction ."
    • Reaction (Mech) The force which a body subjected to the action of a force from another body exerts upon the latter body in the opposite direction. "Reaction is always equal and opposite to action, that is to say, the actions of two bodies upon each other are always equal and in opposite directions."
    • Reaction (Chem) The mutual or reciprocal action of chemical agents upon each other, or the action upon such chemical agents of some form of energy, as heat, light, or electricity, resulting in a chemical change in one or more of these agents, with the production of new compounds or the manifestation of distinctive characters. See Blowpipe reaction Flame reaction, under Blowpipe, and Flame.
    • ***
Century Dictionary and Cyclopedia
  • Interesting fact: Left-handed people are better at sports that require good spatial judgment and fast reaction, compared to right-handed individuals
    • n reaction Any action in resistance or response to the influence of another action or power; reflexive action or operation; an opposed impulse or impression.
    • n reaction In dynamics, a force called into being along with another force, being equal and opposite to it. All forces exist in pairs; and it is a fundamental law (Newton's third law of motion) in mechanics that “action and reaction are always equal and contrary,” or that the mutual actions of two bodies are always equal and exerted in opposite directions. This law was announced, in the form that the quantity of motion is preserved in all percussion, simultaneously in 1669 by Christian Huygens, John Wallis, and Sir Christopher Wren, but was experimentally proved by Wallis only.
    • n reaction Action contrary to a previous influence, generally greater than the first effect; in politics, a tendency to revert from a more to a less advanced policy, or the contrary.
    • n reaction In chem., the mutual or reciprocal action of chemical agents upon each other.
    • n reaction total loss of irritability of the nerve below the lesion; on direct stimulation of the muscle
    • n reaction loss of irritability for very brief currents, such as induction-shocks;
    • n reaction retention and even increase of irritability for making and breaking of currents of longer duration (this galvanic irritability also becomes lost in the terminal stages of the severest forms);
    • n reaction increase of irritability for making currents at the anode as compared with the cathode, so that the anode closing contraction may exceed the cathode closing contraction;
    • n reaction a sluggishness of contraction and relaxation.
    • n reaction In pathology, the response of a nerve or muscle to an applied stimulus.
    • n reaction In serumtherapy, the occurrence of an interaction between two substances, as between an agglutinin and an agglutinable substance, or between toxin and antitoxin.
    • n reaction of measuring the rate of certain psychical and psychophysical processes.
    • ***
Chambers's Twentieth Century Dictionary
  • Interesting fact: The green ring that is formed around the yolk of eggs that have been cooked too long is formed by the chemical reaction from the iron in the yolk and the sulphur in the white part of the egg
    • n Reaction action resisting other action: mutual action: backward tendency from revolution, reform, or progress
    • ***


  • Robert Conklin
    Robert Conklin
    “It's not the situation. It's your reaction to the situation.”
  • James Baldwin
    “We have all had the experience of finding that our reactions and perhaps even our deeds have denied beliefs we thought were ours.”
  • Picabo Street
    Picabo Street
    “When someone tells me there is only one way to do things, it always lights a fire under my butt. My instant reaction is, I'm going to prove you wrong!”
  • Helen Rowland
    “What a man calls his conscience is merely the mental action that follows a sentimental reaction after too much wine or love.”
  • Plato
    “Excess generally causes reaction, and produces a change in the opposite direction, whether it be in the seasons, or in individuals, or in governments.”
  • Reinhold Niebuhr
    “Our age knows nothing but reaction, and leaps from one extreme to another.”


Knee-jerk reaction - A knee-jerk reaction is an instant, instinctive response to a situation.


Webster's Revised Unabridged Dictionary
Cf. F. réaction,


In literature:

His memories, his experiences, his actions and reactions, his life.
"The Short Life" by Francis Donovan
The reaction made in favour of my mother.
"The King's Mirror" by Anthony Hope
But you will take full note of his reactions, Mr.
"The Aliens" by Murray Leinster
Everybody was expected to produce the same reaction under the allusion.
"Folkways" by William Graham Sumner
Byron represented a skeptical reaction against the conventional manners and beliefs of his day.
"Elementary Guide to Literary Criticism" by F. V. N. Painter
The reaction against Robespierre was one of universal fear.
"The Life of Napoleon Bonaparte" by William Milligan Sloane
And, even if they only suspected, what would be their reaction?
"Anything You Can Do ..." by Gordon Randall Garrett
The the reaction swept her in a great flood.
"The Snowshoe Trail" by Edison Marshall
The extravagances of sentiment produced a natural reaction.
"A History of French Literature" by Edward Dowden
The swift reactions occurring among our children are not merely an external manifestation of the intelligence.
"Spontaneous Activity in Education" by Maria Montessori

In poetry:

I note your infinite reactions - In glassware
And sequin
And puddles
And bits of jet - And here and there a diamond…
"To The Others" by Lola Ridge

In news:

That was the reaction I just got from co-workers upon showing them these hot shots of Chace Crawford, all slicked back - rockabilly style.
Researchers have previously speculated it may trigger some reaction in the recesses of our bodies — a vestigial reflex — because the sound resembles that of a primate's warning call.
To Tell Substrates Apart, Enzyme Switches Reactions.
Chemical reaction at OU campus.
Building on OU campus evacuated after chemical reaction .
From yellow to brown, chemical reaction degrades van Gogh's paintings.
Be sure to leave your comments on our Chemical Reaction blog.
Participate In The Chemical Reaction .
Love Is a Chemical Reaction , Scientists Find.
Scientists Tie Chemical Reaction to Creation of Smog.
Realizing that this isn't the usual reaction from a choreographer , he laughed.
Four teens hospitalized after bad reaction to chugging cough syrup.
Mixed reaction to Rhee resignation.
Gainesville City Commissioners' Reactions to New Police Chief.
The idea was to walk into Dreamland , the iconic Tuscaloosa rib joint, wearing the ultimate Gator symbol — a Tim Tebow jersey — just to see what sort of reaction I would get from Alabama fans.

In science:

Obviously in such a case the reaction coordinate has to be redefined in such a way that the new coordinate is monotonic along the reaction path indeed.
Magnetization reversal times in the 2D Ising model
The media where these reactions takes place are usually disordered and reaction-subdiffusion models should provide a better description of these processes.
Some exact results for the trapping of subdiffusive particles in one dimension
Other of the key reactions found by The et al. (1998) had similar sensitivities of 44Ti yield to reaction rates; therefore, if other experimental reaction rates are also a factor of ∼ 2 different from the theoretical calculations, we can expect similar ∼ 25% effects on the 44Ti yield.
Are Ti44-Producing Supernovae Exceptional?
The weak reaction rates n ↔ p are calculated by numerical integration of the electron, positron and neutrino Fermi distributions and phase space for the six weak interaction reactions.
Coupled Variations of Fundamental Couplings and Primordial Nucleosynthesis
Next, it is determined which reaction is realized based on the probabilities proportional to the cross section of each reaction mode at s.
Cosmogenic neutrinos as a probe of the transition from Galactic to extragalactic cosmic rays