Obsessive compulsive disorder is an anxiety disorder characterized by intrusive thoughts producing feelings of unease, apprehension, fear, or worry, and by repetitive behaviors. Symptoms of the disorder can include excessive washing or cleaning, repeated checking, extreme hoarding, preoccupation with sexual, violent or religious thoughts, relationship-related obsessions, aversion to particular numbers and rituals, such as opening and closing a door a certain number of times before entering or leaving a room.