fight-or-flight

noun
  1. (modifier) involving or relating to an involuntary response to stress in which the hormone adrenaline is secreted into the blood in readiness for physical action, such as fighting or running away
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

Examples from the Web for fight-or-flight

Contemporary Examples of fight-or-flight