Obsessive-compulsive disorder(OCD) consists of recurring obsessions and /or compulsions. Obsessions are recurring thoughts or images about specific things that trigger feelings of disgust. Common obsessions include fears around germs, dirt or violence. Compulsions are thoughts or actions that people feel they must do or repeat. A compulsion is usually a response to ease the anxiety of an obsession, eg repeatedly washing your hands to deal with an obsession about dirt.
Attribution: BUPA