defense mechanism (US) or Brit defence mechanism noun
plural ∼ -nisms [count] technical 1 : a process in the brain that makes you forget or ignore painful or disturbing thoughts, situations, etc.
▪ She is projecting her anger on you as a defense mechanism. 2 : a reaction in your body that protects against disease or danger
▪ the cell's normal defense mechanisms against infection
▪ She is projecting her anger on you as a defense mechanism.
▪ the cell's normal defense mechanisms against infection
