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re·ac·tiv·i·ty (.)rē-.ak-'tiv-ət-ē n, pl -ties the quality or state of being reactive <skin \reactivity> <emotional \reactivity>
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re·ac·tiv·i·ty (re″ak-tivґĭ-te) 1. the process or property of being reactive. 2. in electroencephalography, the capability of alternation of a given pattern of electrical activity upon sensory stimulation or other physiological change.Medical dictionary. 2011.