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

This suggests that salt isn’t directly causing damage to the vascular lining but that the real culprit may be the body’s own defense mechanism, the researchers noted. —Khloe Quill, FOXNews.com, 22 Apr. 2026

Google also relies on several other defense mechanisms, like an expansive advertiser verification program, that work together to fortify protections. —ABC News, 16 Apr. 2026

Mark loves to be thought of as untouchable, but that’s a defense mechanism. —Brian Moylan, Vulture, 10 Apr. 2026

That waxy layer on leaves is a natural defense mechanism for plants — and dish soap strips it away, giving the vinegar or other active ingredients direct access to do their work. —Lauren Jarvis-Gibson, Miami Herald, 26 Mar. 2026

Word History

First Known Use

1909, in the meaning defined at sense 1

Rhymes for defense mechanism

• abolitionism
• aldosteronism
• americanism
• anticommunism
• antisemitism
• antiterrorism
• bioterrorism
• colloquialism
• colonialism
• consequentialism
• contextualism
• conventionalism

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