Definitions

"L" lesbian, dyke, gay woman, homosexual woman
Woman whose primary emotional and physical attractions are for other women.

"G" gay, homosexual, fag, faggot
Man whose primary emotional and physical attractions are for other men.

"B" bisexual, AC/DC
Man or woman with strong emotional and physical attracts to both men and women.

"T" transsexual, transgender, trans, ftm, mtf, transvestite, cross dresser, drag queen
But what do these mean? There is no one accepted definition.

The Social Work/Psychology fields treat Transgender and Transsexual as two separate issues. Transgender describes people who are not comfortable with the gender expression which their culture has assigned to them. (i.e. they are not comfortable or can't relate to the roles, clothes, or behaviors that are expected in someone of their sex.) Transsexual describes someone who is not comfortable in their body and feels that they were born into a body of the wrong sex.

Many popular works use Transgender as a continuum that goes from "mild" (cross-dressing) to "severe" (changing the body by surgery or hormones)

The Library of Congress does not distinguish between Transsexual and Transgender and uses Transsexual to cover both.

Other terms

"I" Intersexed, hermaphrodites
People born with some physical aspects of both sexes.

"Q" Queer, questioning
Any/all of the above

and, of course "H" Heterosexuals, hets, straight, breeders
People whose primary emotional and physical attractions are for people of the opposite sex.

Definitions Library of Congress Print Resources Online ResourcesDatabases