defense mechanism

noun

1
: an often unconscious mental process (such as repression) that makes possible compromise solutions to personal problems
2
: a defensive reaction by an organism

Examples of defense mechanism in a Sentence

She is projecting her anger on you as a defense mechanism. the cell's normal defense mechanisms against infection
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.
Several years ago, a tree expert of some sort told me the main reason oaks didn’t produce acorns every year is because of a natural defense mechanism. — Colin Moore, Outdoor Life, 2 Sep. 2026 On Podium, Cheekface dial up both the hooks and the sociopolitical dread, but absurdist humor remains their defense mechanism for a world spiraling out of control. — Zach Schonfeld, Pitchfork, 3 Aug. 2026 This ritual acts as a defense mechanism, creating visible motion to absorb pressure while the fundamental structure remains unchanged. — Vibhas Ratanjee, Forbes.com, 31 July 2026 One of the body’s natural defense mechanisms against a virus like COVID or influenza is the release of cytokines, proteins that act as chemical messengers helping to coordinate the immune system’s response. — Los Angeles Times, 15 June 2026 See All Example Sentences for defense mechanism

Word History

First Known Use

1909, in the meaning defined at sense 1

Time Traveler
The first known use of defense mechanism was in 1909

Rhymes for defense mechanism

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Browse Nearby Words

defenseman
defense mechanism
defensibility
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Cite this Entry

“Defense mechanism.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/defense%20mechanism. Accessed 6 Sep. 2026.

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Medical Definition

defense mechanism

noun
1
: an often unconscious mental process (as repression, projection, or sublimation) that makes possible compromise solutions to personal problems
2
: a defensive reaction by an organism

More from Merriam-Webster on defense mechanism

Britannica.com: Encyclopedia article about defense mechanism

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