defense mechanism

WordReference Random House Learner's Dictionary of American English © 2026

deˈfense ˌmech•an•ism, n. [countable]

1. Psychology an unconscious process, such as denial, that protects an individual from unacceptable or painful ideas or impulses.

WordReference Random House Unabridged Dictionary of American English © 2026

defense′ mech′anism, 

1. Physiology the defensive reaction of an organism, as against a pathogenic microorganism.
2. Psychology an unconscious process, as denial, that protects an individual from unacceptable or painful ideas or impulses.
• 1890–95