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unconditioned response

noun
  1. a reflex action innately elicited by a stimulus without the intervention of any learning processAlso called (esp formerly): unconditioned reflex Compare conditioned response
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
unconditioned response in Medicine

unconditioned response

n.
  1. A natural, usually unvarying response evoked by a stimulus in the absence of learning or conditioning.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.