Abnormal behavior may be defined as behavior that is disturbing (socially unacceptable), distressing, maladaptive (or self defeating), and often the result of distorted thoughts (cognitions).

    The definition of the word abnormal is simple enough but: what is normal? Whose norm? For what age? For what culture?

    The concept of abnormality is imprecise and difficult to define. Examples of abnormality can take many different forms and involve different features, so that, what at first sight seem quite reasonable definitions, turns out to be quite problematical. There are several different ways in which it is possible to define ‘abnormal’ as opposed to our ideas of what is ‘normal’.

Considerations that define abnomallity:
 
Statistical or Social Norm Deviiance: Under this definition of abnormality, a person's trait, thinking or behavior is classified as abnormal if it is rare or statistically unusual.
Situational Context: Under this definition, behavior that goes against common or majority or presumed standards of behavior. For example, one might be judged abnormal in one's failure to behave as recommended by one's family, church, employer, community, culture, or subculture.
Subjective Discomfort can be defined by a person's feeling of abnormality, including feelings of anxiety, strangeness, depression, losing touch with reality, or any other sensation recognized and labeled by an individual as out of the ordinary.
Inability to Function Normally: Under this definition, a person is considered abnormal if they are unable to cope with the demands of everyday life (maladaptive behavior).

   An eclectic approach when determining abnormal behavior seems reasonable.

   A Working definition of a Psychological disorder (abnormality): any pattern of behavior that causes people significant distress, causes them to harm themselves or others, or harms their ability to function in daily life.