Queersecrets Sucks: What not to call trans people:

Avoid: transman, transwoman, trans-man, trans-woman, etc.
Instead, use: trans man, trans woman, etc.
Why?: The one-word “transwoman” and hyphenated “trans-woman” imply that trans is a gender different from woman. The space indicates that it’s an adjective describing a woman, such as “Asian man”…

You know what’s even more interesting than my previous reply on this topic is that earlier tonight I was at a meeting of five FTM folk that agreed that “an FTM” is not only OK, but better than “trans man” or “trans male” because the latter do not describe all of them as accurately as “FTM”—and as a noun.