In strict terms, dysmorphia refers to something that is out of proportion or misshapen. Psychologically, it is usually used to refer to an obsessive, mistaken belief that some feature of the body is out of proportion. In general, observers do not see the imperfection that seems so obvious to a person struggling with a form of dysmorphia.
Body dysmorphic disorder (BDD) describes a belief that some part of the body is hopelessly disgusting. Many with BDD desire plastic surgery, whether for the nose, the ears, or any other body part, but the surgery generally does not stop the obsession.
Two examples of dysmorphia (a number of others exist), both of which might be classified under BDD:
- Muscle dysmorphic disorder (MDD), also known as bigorexia, describes an obsession to gain muscle, with the belief that one's body simply isn't muscular enough.
- Acne dysmorphia is the belief that one's skin has terrible acne.

