1. (n.) Any action in response to another action or force\; counter tendency; movement in a contrary direction; reverse action.

2. (n.) 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 Flame.

3. (n.) 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.

4. (n.) The force which a body subjected to the action of a force from another body exerts upon the latter body in the opposite direction.

5. (n.) Backward tendency or movement after revolution, reform, or great progress in any direction.

Bourbonism Toryism acknowledgment action and reaction aeromotor affect affection answer answering antagonism antipathy antiphon assumption attitude back answer back talk backchat backlash backset backsliding backward motion backward step backwardness backwash brain disease challenge clashing climate of opinion clout collision combative reaction comeback common belief community sentiment compensation complaint conceit concept conception conclusion conflict confutation consensus gentium conservatism conservativeness consideration contradiction contraposition contrariety counteraction counterbalance counterposition counterworking crack-up crankiness crotchetiness defiance demur die-hardism dispute dissent dissentience echo effect emotion emotional charge emotional disorder emotional instability emotional shade estimate estimation ethos evasive reply experience extreme right extreme right wing extreme rightism eye feedback feeling feeling tone force foreboding fractiousness friction functional nervous disorder general belief gut reaction heartthrob idea impact impress impression imprint insanity interference jet power jet propulsion judgment kick know-nothingism laissez-faireism lapse lights maladjustment manic-depressive psychosis mark melancholia mental disorder mental illness mind monarchism mystique negativism nervous breakdown nervous disorder neurosis nonconformity noncooperation notion objection observation obstinacy old school tie opinion opposition opposure oppugnance oppugnancy paranoia passion passive resistance personal judgment personality disorder perverseness point of view popular belief position posture power plant presentiment presumption prevailing belief print problems in living profound sense protest psychosis public belief public opinion radical rightism ram-jet propulsion reaction propulsion reactionariness reactionaryism ready reply rebuff recalcitrance recalcitrancy recalcitration receipt recession recidivation recidivism reciprocation recoil reentry reflex refluence reflux refractoriness regress regression rejoinder relapse reluctance remonstrance renitence renitency repartee repellence repellency repercussion replication reply repost reprisal repugnance repulse repulsion rescript rescription resistance resojet propulsion respondence response responsion responsory retaliation retort retroaction retrocession retroflexion retrogradation retrogression retrusion return revenge reverberation revolt rightism riposte rocket power rocket propulsion rollback royalism schizophrenia sensation sense sentiment setback short answer sight snappy comeback social Darwinism social maladjustment stance stand standpattism sternway swimming upstream theory thinking thought throwback turbojet propulsion ultraconservatism uncooperativeness undercurrent unprogressiveness view way of thinking withstanding witty reply witty retort yes-and-no answer