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.
This finding suggests that for people with avoidant attachment styles, the ick could manifest as a defense mechanism against emotional closeness. Mark Travers, Forbes.com, 22 Apr. 2025 This natural defense mechanism has grabbed our attention this spring, since our weather patterns have lent a hand in amplifying a natural phenomenon. Heather Zidack, Hartford Courant, 12 Apr. 2025 In certain people, this sets off a response from the immune system, the body's defense mechanism. Janet Loehrke, USA Today, 2 Apr. 2025 Inspired by Conan’s defense mechanisms, researchers are developing synthetic antioxidants that could protect astronauts from intense cosmic radiation on long-duration missions, or safeguard first responders in radiation accidents here on Earth. Scott Travers, Forbes, 24 Mar. 2025 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

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Cite this Entry

“Defense mechanism.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/defense%20mechanism. Accessed 14 May. 2025.

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

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