There is a wide variety of terms — often ambiguous, complex, and newly-coined ones — to describe trans experience and identities. Included among this list will be some fairly simple explanations; if a term is hotly debated, I will say so, and not bother to explain the details very clearly.
I'm also taking the liberty of defining a few words that you're no doubt familiar with ("gender" and "sex" and so on, and other words like "pass" or "stealth"), as they may have connotations in the trans community that most people don't normally associate them with.
Click one of the underlined letters below to take you to the beginning of that letter's particular section.
An ally, in this context, refers to a cisgender (see below) person who fully supports the rights of trans people, treats their genders with respect, and actively helps work against transphobia. Allies are educated about trans issues and are willing to speak up against discrimination.
Androgyny is the quality exhibited by people who are difficult to identify as either clearly male or clearly female. Some trans people whose genders cannot be classified as strictly male or strictly female call themselves androgynes.
Assignment of gender refers to the way that we assume others' genders based on their bodies. When a child is born, our culture slots it into one of two groups: male or female, avoiding all overlap. We "determine" the child's "correct" identity based on a quick visual assessment of the appearance of its sexual organs, and we do so by following a specific dichotomy. (A vulva-bearing child is typically assigned female at birth, or AFAB, for short. A penis-bearing child is typically assigned male at birth, or AMAB.) Gender assignment mostly tends to work out for those involved, but many trans people are notable exceptions to this.
Cisgender is a word used to describe people who are not transgender; likewise, cissexual describes the non-transsexual. This word is a simple opposite, formed by using the prefix "cis" (on the same side/not "across") as opposed to "trans" (across/beyond).
Coming out, in reference to trans people, can have two separate meanings:
Crossdressing is a term that describes the practice of using clothing tailored toward the wearer's "opposite" gender. Men who dress this way would wear clothes made for women, and vice versa. A desire to crossdress isn't uncommon in straight cisgender males — some crossdressers, however, would characterize themselves as transgender. Sometimes crossdressers are called CDs for short.
Drag is a type of performance that features crossdressed people; women who perform drag are called drag kings, and men drag queens. (Note that not all crossdressing is part of a drag act.) Kings and queens are often lesbian or gay, though not always — many identify with other sexual orientations. Some drag performers would call themselves trans, and some would not.
Dysphoria, in this context, describes a variety of negative feelings that are related or connected to someone's gender or sex. Trans people who experience dysphoria may be profoundly uncomfortable with certain aspects of their bodies, particularly sex characteristics. They may also have a strong aversive reaction — perhaps sadness, or anger, or disgust — upon being called by the (inappropriate) pronouns of their birth-assigned genders, or the inappropriate-gender names that were used for them before they came out.
Femininity refers to qualities that are thought of as being womanly, that are typically ascribed to women, and that are considered to be socially appropriate for a woman's behavior. People who exhibit self-described femininity do not necessarily think of themselves as women: some men (including trans men) are feminine, some women are, some genderqueer or androgynous people are.
Female-to-male (FTM, FtM, F2M) is an adjective or noun for men whose bodies were initially assigned female. These men often undergo the social and/or medical transition that the acronym implies.
Gender refers to the sociological set of boundaries and signifiers that may define people as being feminine, masculine, or androgynous. When you look at someone and decide that she's a girl, based on her appearance, behavior, and presentation of self, you're judging her gender (not her sex).
The gender binary is a very common system of thought, referring to certain ideas that many people hold about gender and sex. The gender binary is not correct. It presumes that everyone is either male or female (not so!), and it implies that trans people flat-out do not exist. It is based on the following three principles:
More accurately, it could instead be said that:
Gender identity describes the psychological recognition of oneself as being a member of a certain gender. Gender identity is determined by a person's internal perceptions; it is separate from physical sex, which is an absolute that's determined before birth.
Gender-neutral pronouns are used to avoid referring to someone as "he/him" or "she/her." Some people explicitly ask for gender-neutral pronouns, as these are the most comfortable for them; other people will use them as generics. A short list of the most common gender-neutral pronouns:
They smiled • I called them • their cat purred • it's theirs • they like themselves
Sie, hir (pron. see/hear)
Sie smiled • I called hir • hir cat purred • it's hirs • sie likes hirself
Zie, zim (like he/him, but with a "z" at the front)
Zie smiled • I called zim • zir cat purred • it's zirs • zie likes zirself
Ey, em (like they/them without the "th")
Ey smiled • I called em • eir cat purred • it's eirs • ey likes emself
Gender presentation refers to the way a person looks, dresses, or acts; it describes the "gender signifiers" that are part of their external appearance or mannerisms. Drag kings who wear stick-on beards, for example, are deliberately trying to make their gender presentations as masculine as possible.
Genderqueer is an identity taken on by a variety of people who feel that, in some way, the very substance of their genders lies outside the gender binary's two labels of "male" and "female."
Gender role describes the set of expectations that are ascribed to a certain gender in any given culture, relating to how to people of that gender "should" (among other things) behave, talk, dress, and think.
Masculinity refers to qualities that are thought of as being manly, that are typically ascribed to men, and that are considered to be socially appropriate for a man's behavior. People who exhibit self-described masculinity do not necessarily think of themselves as men: some women (including trans women) are masculine, some men are, some genderqueer or androgynous people are.
Non-op, short for non-operation, describes people who don't plan to undergo any surgery related to their trans status. There are a variety of reasons for this decision, ranging from pervasive medical difficulties to discontent with the surgical results to simple lack of desire.
A person who passes, although assigned with one physical sex, is able to resemble the other sex closely and convincingly in the public eye. This word is technically a misnomer; trans people who "pass" are not doing so as trickery or disguise, but rather revealing their actual genders.
Post-op is a simple descriptive term used for people who have completed all the sex reassignment surgery that they plan to undergo.
Pre-op, likewise, refers to people who wish/plan to have surgery, but who have not yet undergone it.
Sex refers to various qualities displayed by the human body that, strictly medically speaking, define people as being male, female, or intersex. When you decide that a someone's sex is female, you're mentally juggling many different traits of her physical self — her genitals, her hormone levels, her chromosomes, her internal sex organs, her secondary sex characteristics — and finally making the judgment call that her body can be, as a whole, classifiable as "female" according to the normative standards of medical science. (Note that the "scientific standards" of sex are at least partly culturally determined, according to a society's notion of what makes a body male or female.) Sex is distinct from gender.
Sexual orientation refers to, simply, towards whom someone's sexual desires and drives are oriented — perhaps towards only women, or only men, or towards nobody, or regardless of gender. It is separate and independent of gender identity.
Sex[ual] reassignment surgery refers to several types of operations; it is typically used to describe vaginoplasty (the creation of a vagina), metoidioplasty and phalloplasty (two ways to create a penis), and mastectomy (removal of the breasts, typically in a trans man). Certain other surgeries, involving removal of various parts of the internal reproductive system, are also often considered forms of SRS.
Stealth is a descriptor of people who, after beginning transition and living in their preferred genders, do not readily tell others about their upbringings or past lives within the birth-assigned gender. Some people are only comfortable when living in "deep" stealth, some practice stealth to a degree, and some choose to be more or less open about their trans statuses.
Transgender is an umbrella word that refers to all the folks who, more or less, either
Some people who fall under these categories do not define themselves as transgender, for a span of different reasons, mostly having to do with personal preference and experience. When in doubt, ask the individual.
Transition refers to the process of changing one's living situation so that it suits the individual's gender identity more accurately. It can entail quite a lot of different actions, ranging from a social name-change to sex reassignment surgery, and has been given its own section on this website so that I may explain it in more detail.
Transsexuality describes the condition of being described/assigned as a medically typical "male" or "female" at birth, but having an identity that lies exclusively or near-exclusively within the gender that people tend to call opposite. A transsexual man was initially assigned female, and was probably raised within the female gender; vice versa with a transsexual woman. Transsexual-identified people often undergo a social/physical transition in order to live more comfortably within their true genders.
Transvestism is a rather outdated word that is equivalent to "crossdressing," and is usually used in reference to men who dress as women. Its use should be avoided, as some find it offensive.