A transsexual person is someone who experiences a gender identity that is inconsistent with their assigned sex or gender, and desires to permanently transition to the sex or gender with which they identify, usually seeking medical assistance (including gender affirming therapies, such as hormone replacement therapy and gender affirming surgery) to help them align their body with their identified sex or gender.
The term transsexual is a subset of transgender, but some transsexual people reject the label of transgender. A medical diagnosis of gender dysphoria can be made if a person experiences marked and persistent incongruence between their gender identity and their assigned sex.