From Longman Dictionary of Contemporary Englishdefence mechanismdeˈfence ˌmechanism British English, defense mechanism American English noun [countable] 1 MPa process in your brain that makes you forget things that are painful for you to think about2 HBHa reaction in your body that protects you from an illness or danger
Examples from the Corpus
defence mechanism• I note this, and harp on her imperfections, as a defence mechanism.• What appears to be contrary can always be assimilated as evidence of repression, or as a defence mechanism.• Inflammation is another internal defence mechanism and is a reaction of living tissue to infection, injury and irritants.• And if our defence mechanism is impaired, what other dangers may we not be open to?• Where did she get this automatic shutdown defence mechanism?• The sea slugs therefore use the defence mechanism of another creature for their own defence. 