An ego defense mechanism is a psychological mechanism that is used to protect oneself from negative emotions or situations. Synonyms for ego defense could include coping mechanism, self-protection, defense mechanism, psychological shield, self-preservation, or self-defense. These terms are often used interchangeably and describe the various ways in which an individual will protect themselves from psychological harm. Some examples of ego defense mechanisms include denial, rationalization, projection, and displacement. Each mechanism serves as a means of shielding the mind from unpleasant emotions, and while they can be helpful in the short-term, overuse of these mechanisms can lead to psychological distress and problems.