The behavior of performing an act persistently and repetitively without it leading to reward or pleasure. The act is usually a small, circumscribed behavior, almost ritualistic, yet not pathologically disturbing. Examples of compulsive behavior include twirling of hair, checking something constantly, not wanting pennies in change, straightening tilted pictures, etc.

An anxiety disorder characterized by recurrent, persistent obsessions or compulsions. Obsessions are the intrusive ideas, thoughts, or images that are experienced as senseless or repugnant. Compulsions are repetitive and seemingly purposeful behavior which the individual generally recognizes as senseless and from which the individual does not derive pleasure although it may provide a release from tension.

An animal's cleaning and caring for the body surface. This includes preening, the cleaning and oiling of feathers with the bill or of hair with the tongue.

An act performed without delay, reflection, voluntary direction or obvious control in response to a stimulus.

Disorder characterized by an emotionally constricted manner that is unduly conventional, serious, formal, and stingy, by preoccupation with trivial details, rules, order, organization, schedules, and lists, by stubborn insistence on having things one's own way without regard for the effects on others, by poor interpersonal relationships, and by indecisiveness due to fear of making mistakes.