REACTION

noun Date: circa 1611 1. the act or process or an instance of reacting, resistance or opposition to a force, influence, or movement, a response to some treatment, situation, or stimulus , bodily response to or activity aroused by a stimulus:, an action induced by vital resistance to another action, depression or exhaustion due to excessive exertion or stimulation, heightened activity and overaction succeeding depression or shock, a mental or emotional disorder forming an individual's response to his or her life situation, the force that a body subjected to the action of a force from another body exerts in the opposite direction, 5. a. chemical transformation or change ; the interaction of chemical entities, the state resulting from such a ~, a process involving change in atomic nuclei