A transsexual is someone who feels her/his true gender is not the same as her physical sex.

The medical definitions:

The term transsexual was coined by Dr. Harry Benjamin in the 1950s and used in his book The Transsexual Phenomenon.

The DSM-IV prefers the term Gender Identity Disorder or GID, insinuating that there is something "wrong" with anyone who feels her body's sex doesn't match her mind's gender. It seems to have a bit of trouble differentiating between gender and sexuality too. In fact, many surgeons who mutilate intersexed babies believe they were successful only if the child grows up into a healthy, straight adult of a binary sex and gender.

Transsexuals used to be given electric shock "therapy" to try and convince them they were really deluded about their gender. Needless to say, this method yielded no positive results.

There seems to be evidence now showing that transwomen (Those that identify as women despite being biologically male) have the same sized hypothalamus as genetic females, which is drastically different to that of males. This means there may be some truth to the notion that transsexuals really are the gender they believe themselves to be.

The life of a hypothetical transsexual:

The basic life of a transsexual is something like this: You're born, and someone says "It's a boy!" or "It's a girl!", only it isn't. Either you get into trouble for doing inappropriate things and wearing inappropriate clothes for your sex, or you live happily for a while, blissfully unaware that anything's askew. Then puberty hits. You may be depressed, even suicidal, and might self mutilate every now and then. Eventually you'll get yourself sorted and find a psychiatrist who can help you and give you hormones. Then you transition, living as your real gender, and eventually look like your real gender too. This can take a while and/or cost a lot. At this point your family may disown you and your friends may ostracize you, but don't worry. If they do, you'll get better ones who like you for who you are, not who you pretend to be. After a year of living in your chosen gender role, AKA the real life test, you can have sex reassignment surgery (If you want to; many transsexuals now opt to be non-op for various reasons) for a mere ten thousand pounds (If you live in the UK, that is. It's a lot of money, anyway). If you're lucky you might even fall in love with someone, but if they don't run away screaming or hurt you when you tell them your past, you can't marry them. Legally, you can never be male or female again if you want to do something like get married. (Update: this is now thankfully out of date, at least in the UK and Australia.)

What a transsexual isn't:

• Gay Well, some might be, but if you're biologically male and your gender is female, and you're attracted to men, you're straight. OK, so most of my transsexual friends are lesbians, but that's beside the point. Likewise, genetic female transsexuals who identify as men are not lesbians, they are either straight or gay men.
• A transvestite Transvestism and transsexualism are completely different. The former involves wearing clothes of the opposite gender for sexual thrills. The latter involves wearing clothes of what you believe is your actual gender because it feels right.
• Mad Despite what doctors used to think.
• A pervert Well, again, some are, like with any subcategory, but transsexualism itself doesn't make you perverted. In fact, it's not even a sexuality despite the confusing name. (See "What the word means" below.)

What a transsexual is:

• Male or female Transsexuals aren't always women with male bodies. Some are men with female bodies. The latter just don't make it onto talk shows as often, but they do exist.
• Shy They are most likely shy and low on self esteem, and might be low on social skills too. If you hated your body for a substantial part of your life, and had trouble differentiating between that and hating yourself, wouldn't you be?

Who to ask if you think you might be a transsexual:

• The COGIATI The web site transsexual.org has a test called the COGIATI which guesses your gender based on your answers to various questions. Although not very authoritative, it can be fairly useful.
• A psychiatrist who will probably refer you to another, more gender knowledgable psychiatrist, who may or may not give you hormones and/or ask you to start living your life in your true gender for a long time beforehand.
• Yourself Deep down, you know you're the only person who can really tell if you're a transsexual or not. No one else knows. You just have to be honest with yourself.

Recommended reading:

• Mildred L. Brown, Chloe Ann Rounsley: True Selves: Understanding Transsexualism - For Families, Friends, Coworkers, and Helping Professionals
• Kate Bornstein: Gender Outlaw: On Men, Women and the Rest of Us
• Riki Anne Wilchins: Read My Lips: Sexual Subversion and the End of Gender

What the word means:

OK, there seems to be a bit of confusion over the meaning of the word transsexual, so I'll try and clear it up. Please message me if I've made any mistakes.

For subjects people don't really feel comfortable talking about, they seem to pick Latin words to describe them. So you get phrases like trans (crossed) sexual (something to do with sex). Both of these words are a bit ambiguous. "Crossed" doesn't mean you cross from male to female, or from female to male; it means your gender is one and your physical sex is the other, hence they are crossed. "Sexual" causes even more confusion. It means something to do with sex, but in English sex can mean several things. In this context, it doesn't mean the action of sex, it means your gender or your body's physical sex. So while it might sound like the word could mean "someone who gets aroused by changing from male to female," it actually means "someone whose gender and sex are different from each other." Hence it has nothing to do with sexuality in the sense of what turns you on, even though it has the phrase "sexual" in it.

Hopefully I didn't make that even more confusing.

A lot of people whom Zoeb refers to as transsexual above, are now also referred to as transgendered.

That is, in general, 'transsexual' may be used to describe a person who has transitioned, whereas 'transgendered' refers to all persons who have have gender issues, Gender Identity Disorder and/or are other gendered, as well as transsexuals as defined above.

However, a movement has arisen for some post-transition people to call themselves 'persons of transsexual history' or 'persons who have experienced transsexualism'. The idea is that 'transsexualism' is a condition you have, not the person you are, and should be treated linguistically and clinically in the same way as schizophrenia or diabetes or epilepsy: You are a 'person who has schizophrenia', you're not 'a schizophrenic', etc. Likewise this medical model of transsexualism recognises it as a medically treatable condition, and some groups will even go so far as to say that a person who has transsexualism will require medical treatment (Sex Affirmation Treatment) in the form of hormone therapy and or surgery (aka Sex Reassignment Surgery/SRS or Gender Reassignment Surgery/GRS) in order to survive.

Within this model comes the concept of 'brain sex', which is the concept that our brains have a sex, independent of our bodies. Usually, brain sex and body sex match up, but sometimes, due to reasons yet unknown (perhaps a mis-timing of the hormonal wash in early foetal development?), the brain develops a sex different to the body, therefore producing the condition of transsexualism in a person, which can be seen as a type of intersex.

In this medical model, a person who has transsexualism is a person who will, or has transitioned - and once has done so ceases to be transsexual in the present (thus becoming a person of transsexual history...). A person, therefore, who does not necessarily want or need to physically transition, and/or who sees hirself as a gender other than male/man or female/woman; or a person who transitions, lives wholly within 'man' or 'woman' and still acknowledges him or herself as trans*, is by definition not transsexual.

Marriage:

In Australia, it is legally possible for a transsexual person to get married. This relies on the premise that a post-transition transsexual person is legally the sex s/he presents him or herself, and therefore can marry a person of the opposite sex. The precedent for this was set in a case known as 'Re Kevin', which was fought and won on 12 October 2001 in the Family Court of Australia, a decision which was upheld on appeal in the same court on 23 February 2003.

Ref: http://www.austlii.edu.au/au/cases/cth/family_ct/2001/1074.html

As a rebuttal to Monalisa's node of transsexual in which she writes, "...whereas 'transgendered' refers to all persons who have have gender issues, Gender Identity Disorder and/or are other gendered, as well as transsexuals as defined above." There has been recent scholarship arguing the difference of transgender and transsexual.

In the recent years there have been a small group of academics who have broken from the common practice of utilizing the tools of queer discourse to theorize about transsexual communities and individuals; rather these rogue academics have been critical of queer appropriations of the transsexual through theory and activism. Consequently, the appropriation of the transsexual community within the queer discourse has resulted in the marginalization of certain individuals of the community, namely those who pursue a heterosexual lifestyle post-transition, those who wish to undergo surgical modifications of their bodies to conform to heteronormative ideal of the genital labeling of sex, and individuals who essentialize their gender identity.

As Viviane Namaste states,
"While the term "transgender" is currently one of the most popular, it needs to be pointed out at this point in history that increasingly transsexuals object to being included under a catch-all phrase of "transgender." They argue that the health care and social service needs of transsexuals are quite specific, and that this specificity is lost when people use a vague "transgender." Furthermore, the popularity of the term "transgender" emerges from the Anglo-American lesbian and gay community. While this discourse may have meaning for some transsexuals who understand their lives in these terms, it does not speak to the transsexuals who do not make sense of their lives, and their political struggles, within the confines of a lesbian/gay framework. It is important to point this out, because most of the Anglo-American writers and activists on "transgendered" issues come out of the lesbian/gay community and express themselves in those terms. My empirical research contradicts this underlying assumption, since most of the transsexuals I have interviewed do not articulate their needs according to a lesbian/gay framework. All of this to say that questions of language are deeply political!"¹

There have been increasing numbers of transsexual individuals who have stopped identifying as transgendered, seeing it as a term imposed upon them by an outside community. Transgender should not be thought of a catch-all phrase that embodies all trans-prefixed identities but rather as a political identifications for individuals who wish to queer the binary gender system.

1. Namaste, Viviane. "Addressing the Politics of Social Erasure: Making the Lives of Transsexual People Visible – An Interview With Viviane Namaste." New Socialist Magazine. Issue 39. December 2002-January 2003. 25 Nov 2007. < http://www.newsocialist.org/magazine/39/article04.html>.