First, it should be noted that in the transgendered world, sexual preference is based upon two things: The gender identity of the person, and the gender/gender identity that person is attracted to. They may be homosexual, hetrosexual, or bisexual.

Now, on to the definition of the slang word "Transdyke." It is a derogatory word used to describe a male to female transexual that has a sexual preference for women.

Technically, such a person would be lesbian, or homosexual.

This is similiar to another derogatory term, trannyfag.

If one wants to truly be enlightened, one may wish to consult the Transgender FAQ: http://www.geocities.com/westhollywood/6888/tgfaq.htm

(Well, if we're going to be practical carbon copies of ourselves...; see trannyfag)

Transdyke is only a deragatory word if someone doesn't want it applied to them; the same as the word dyke. That is, one probably shouldn't use it to label other people without their permission, but lots of people use it to label themselves, in which case it is not deragatory, but the reclaiming of a word that was once used against them (much like dyke in general - and in this case that's the reclaimed word since transdyke was never a popular insult for gynephilic MTFs, as far as I know, - nigger, etc.)

Also, sexual orientation identity is not necessarily dependant on the person's gender identity; in fact, it only need be if one identifies with the classical sense of homosexual and heterosexual. Bisexual, asexual, pansexual, polysexual, intellectsexual, queersexual, etc. (as much as your mind can come up with) people can be any gender.

Rather than professing to be the one true deacon of the Transgender Englightenment(tm) and laying down the rules, perhaps we could take the experiences of each person as valid.