Transsexualism: Consistently strong desire to change one's anatomical gender. Some transsexuals were misassigned gender at birth (for example, being anatomically male but raised as female), either on purpose or due to indistinct anatomy. Most, however, are perfectly normal physically. Transsexuals may dress and behave as individuals of the opposite sex, and they may choose to use hormones or surgery to develop desired secondary sex characteristics. Surgery to change the appearance of the external genitals is known as sex reassignment surgery. Surgery and hormonal treatments for gender reassignment are available for both male and female transsexuals. Transsexualism is distinct from transvestitism (cross-dressing), and it does not always indicate a change in the individual's sexual preference.