Any action in resisting other action or force;
counter tendency; movement in a contrary direction; reverse
action.
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.
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.
The force which a body
subjected to the action of a force from another body exerts upon the
latter body in the opposite direction.
Backward tendency or
movement after revolution, reform, or great progress in any
direction.
In celebration of Noah Webster's Birthday (October 16, 2009), we have prepared an updated website. 
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