Medical Definition of hyperreactive
: having or showing abnormally high sensitivity to stimuli Because of their association with the trauma, many victims seem to be hyperreactive to sounds and sights other children don't respond to.—Kate McGraw, The News Journal (Wilmington, Delaware), 29 Apr. 2009 Interior surface cells of the bronchial passages were destroyed and the airways became hyper-reactive to outside stimuli.—Harold M. Schmeck, Jr., The New York Times, 31 Jan. 1989
Seen and Heard
What made you want to look up hyperreactive? Please tell us where you read or heard it (including the quote, if possible).