A defense mechanism is a coping technique that reduces anxiety arising from unacceptable or potentially harmful stimuli. Defence mechanisms are unconscious and are not to be confused with conscious coping strategies. Sigmund Freud was one of the first proponents of this construct. Here is the list of some defence mechanisms:

Compensation

Over-achievement in one area to offset real or perceived deficiencies in another area

‪Conversion

Expression of an emotional conflict through the development of a physical symptom, usually sensorimotor in nature

‪Denial

Failure to acknowledge an unbearable condition; failure to admit the reality of a situation or how one enables the problem to continue

‪‎Displacement

Ventilation of intense feelings toward persons less threatening than the one who aroused those feelings

‎Dissociation

Dealing with emotional conflict by a temporary alteration in consciousness or identity

‪Fixation

Immobilization of a portion of the personality resulting from unsuccessful completion of tasks in a developmental stage

‪Identification

Modelling actions and opinions of influential others while searching for identity, or aspiring to reach a personal, social, or occupational goal

‪Intellectualization

Separation of the emotions of a painful event or situation from the facts involved; acknowledging the facts but not the emotions

‪Introjection

Accepting another person’s attitudes, beliefs, and values as one’s own

‎Projection

Unconscious blaming of unacceptable inclinations or thoughts on an external object

‎Rationalization

Excusing own behaviour to avoid guilt, responsibility, conflict, anxiety, or loss of self-respect

‪Reaction Formation

Acting the opposite of what one thinks or feels

‎Regression

Moving back to a previous developmental stage to feel safe or have needs met

‎Repression

Excluding emotionally painful or anxiety-provoking thoughts and feelings from conscious

awareness

‪Resistance

Overt or covert antagonism toward remembering or processing anxiety-producing information

‪Sublimation

Substituting a socially acceptable activity for an impulse that is unacceptable

‎Substitution

Replacing the desired gratification with one that is more readily available

‎Suppression

Conscious exclusion of unacceptable thoughts and feelings from conscious awareness

Undoing

Exhibiting acceptable behaviour to make up for or negate unacceptable behaviour