This one is my favorite:
transsexual
A transsexual is a person who was assigned one sex at birth (male or female) but who identifies their gender in what society considers the "opposite" direction. There are two general "types" of transsexual: Female-to-Male (FTM) and Male-to-Female (MTF). The former is a person labeled female at birth, but whose gender identity and/or expression lie in masculine or male direction. The latter is a person labeled male at birth, but whose gender identity and/or expression lie in the feminine or female direction.
Many, but not all, transsexual people take social, legal, medical and/or surgical steps to be seen and recognized in society as the correct gender, and to find comfort in their own body. Social steps changing their clothing, hair, mannerisms, speech, etc. to be in line with what society considers appropriate for their true gender; or using other devices to adjust how their bodies appear, such as binding the breasts (FTM) or padding a bra (MTF). Legal steps include changing name and sex on identification, etc. Medical steps include hormone therapy. For MTFs, hormone therapy most typically involves taking estrogen, progesterone and an androgen blocker (usually in pill form)to feminize their body and appearance; for FTMs, hormone therapy involves taking testosterone (usually in injection form) to masculinize their body and appearance. Surgical steps include chest surgery (for FTMs removal of breasts and masculinization of the chest), removal of the gonads (for MTFs, removal of the testes; for FTMs, removal of the uterus, cervix, fallopian tubes and ovaries), facial surgery (for MTFs, to feminize the face, remove the adam's apple, etc.) and "sex reassignment surgery" which involves the creation of a vagina, labia and clitoris from the penis (in MTFs) or the creation of a phallas (in FTMs).
However, having surgery, taking hormones, changing one's appearance or does not make a person any more or less legitimately transsexual than not doing so.
George transitioned from female to male. He is a transsexual