For the band, see Neurotic (band).

The term neurosis, also psychonerosis or neurotic disorder, in modern psychology refers to any mental disorder that, although may cause distress, does not interfere with rational thought or the persons' ability to function. This is in contrast to psychosis which refers to more severe disorders. The term is no longer in common use. The word is derived from two Greek words: neuron (nerve) and osis (diseased or abnormal condition).

A neurosis, in psychoanalytic theory, is an ineffectual coping strategy that Sigmund Freud suggested was caused by emotions from past experience overwhelming or interfering with present experience. For example, someone attacked by a dog as a toddler may have a phobia or overwhelming fear of dogs.

In Carl Jung's theory of analytical psychology a neurosis results from the conflict of two psychic contents, one of which must be unconscious.

There are many different specific neuroses and many of them are named: pyromania, obsessive-compulsive disorder, anxiety neurosis, and an endless variety of phobias.

Everyone has some neurotic symptoms and defense mechanisms which may help them to deal with anxiety. Defense mechanisms which result in difficulties in living are termed neuroses and are treated by psychoanalysis, psychotherapy/counselling or other psychiatric techniques.