: relating to, being, or causing physiological changes in the body (such as an increase in heart rate or dilation of bronchi) in response to stress
epinephrine is a fight-or-flight hormone
a fight-or-flight reaction

Examples of fight-or-flight in a Sentence

Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Neuroimaging reveals why: Self-criticism activates the brain's threat-defense system, flooding the body with cortisol and triggering fight-or-flight responses. Anna Barnhill, Forbes.com, 19 May 2025 Mild anxiety or stress: Mild anxiety or stress can trigger the body's fight-or-flight response, leading to faster, shallower breathing (hyperventilation). Emily Brown, Verywell Health, 14 May 2025 Sympathetic drive — the fight-or-flight response — works like a gas pedal, while parasympathetic drive provides the brake. Rustin Dodd, New York Times, 1 May 2025 Some fears—like the fight-or-flight response—are essential for survival. Benjamin Adams, Forbes.com, 30 Apr. 2025 See All Example Sentences for fight-or-flight

Word History

First Known Use

1973, in the meaning defined above

Time Traveler
The first known use of fight-or-flight was in 1973

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Cite this Entry

“Fight-or-flight.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/fight-or-flight. Accessed 28 May. 2025.

Medical Definition

fight-or-flight

adjective
ˌfī-tər-ˈflīt
: relating to, being, or causing physiological changes in the body (such as an increase in heart rate or dilation of bronchi) in response to stress
the fight-or-flight response
Last Updated: - Updated example sentences
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