(minor edits have been made on May 27, 2012)
The language broader society uses to describe trans people involves denying that we are who we say we are. This is on top of the active misgendering we have to continually deal with. Often people try to fight this linguistic misgendering one word at a time, especially cis people new to learning about it. This is incoherent, at best, especially since new problems are constantly being found and new words coined to replace the old ones.
So, instead of trying to do a vocabulary list or glossary, I’m going to lay out a couple principles. Words will be used as examples to illustrate these principles, but the principles themselves are the central point. The attitudes that cause the use and proliferation of this language are the problem, not the language itself. Also, I’m going to be assuming here that people know that slurs against trans people aren’t acceptable at all, and even a level beyond that, that explicit misgenderings aren’t acceptable.
Trans people’s genders are real
A lot of the language used to discuss trans people de-legitimizes trans peoples’ genders or casts binary trans people as less their gender than cis people of their gender, denying that people whose genders fall outside the binary even are what they say they are, or denying that binary-gendered trans people are actually the same gender as the same binary-gendered cis people. This is, of course, a reflection of the way the general society sees trans people.
Actually, stepping up to a word I used in the last paragraph, “cis” itself was coined along this principle. Its predecessors included “bio” and “genetic”, which implied that there was a biology or genotype that made one a woman or a man; describing someone as a “bio woman” misgenders trans people of all genders; about the only people not misgendered are non-binary-gendered people who were designated male; likewise for “bio man” misgendering everyone except nonbinaries who were assigned female. Worse words it replaced included “natural” and “real”, which are, of course, still in use among cissexist groups.
A more subtle way of de-legitimizing trans people’s genders is to emphasize their trans-ness. There are a number of ways this is done. The most common is treating “trans” as a prefix, rather than a word or an abbreviation (though exactly what it’s an abbreviation for is unclear (both “transgender” and “transsexual” have problems). Saying “transman” instead of “trans man” subtly implies that the trans man is a fundamentally different kind of man than a cis man because he is trans, otherwise he’d be referred to with the same word.
Another, more subtle, form comes about when people will say “trans (wo)man” when simply “(wo)man” will do. Unless it’s relevant, saying “trans” where you wouldn’t say “cis” for a cis person does in fact deny the legitimacy of trans peoples’ genders. I (personal anecdote time!) actually struggle with this myself, so I know exactly what the feeling is where saying simply “man” for a trans man or “woman” for a trans woman feels wrong, or dishonest. I name that feeling “internalized cissexist bullshit” and fight against it.
Corollary: You are not your birth assignment
One of the most common ways of misgendering trans people is to try to cling to their birth assignments when gendering them. This includes the “MTF” and “FTM” language and all its derivatives. Many trans people are beginning to realize that they never needed to identify as their birth assignment because they never were. So if someone was never male, why would it make sense to call her “male to female” or worse “a male to female”?
Certain parts of the trans community do use this language. Many trans guys use “FTM” in a reclamatory way (and many don’t). If someone uses the words this way, more power to them; I don’t use them for myself, and to many trans women (including myself) the label “MTF” is held to be one nonconsensually applied to them. To some people “mtF transsexual” (with mtF as an adjective) is acceptable, or saying “mtF spectrum” for what is more commonly termed “transfeminine spectrum”, although that concept (and the terms “transfeminine” and “transmasculine” themselves) has problems that I’ll address at a later date.
Say what you mean
This applies mostly when talking about bodies and in discussions of other issues; abortion rights, for instance, are a big one in the news today. The most common application of this principle is simple: don’t use gendered words to say something that isn’t gender. Instead, say what you mean. Don’t say “physically male” to mean “has a penis”. If it’s not polite to say what you mean without a gendered euphemism, think very carefully about why you’re saying it; if it’s not polite to say someone has a penis in the company you’re with, why would it be polite to say they’re “physically male”?
For more examples: If something is significant to people who can get pregnant, like, say, abortion rights, it’s significant to people who can get pregnant, not to women even though the overlap between the two groups is enormous. When someone is revealed in a movie or a book or whatever to have a penis, they are revealed to have a penis, not to be a man. Someone with two x chromosomes has two x chromosomes; they are not “genetically female”.
This principle, of course, extends into other things in trans activism and beyond. If you mean “bodily integrity instinct” or “social gender instinct”, say that instead of saying “gender” (I’ve been guilty of making mistakes on this myself).
Following these principles is more important than any amount of vocabulary replacement without them, since it is literally impossible to come up with a comprehensive list of the ways language ungenders or misgenders trans people. Essentially, apply the same concern to your word choice as you would to anything else, and the correct words become natural. Try to change your vocabulary one word at a time, and nothing has changed.