FTM
"Female-to-Male", an adjective sometimes used to describe trans men (people who were assigned female at birth but live and identify as men, and sometimes transition medically), or their transitions. The term is sometimes used as a noun ("an FTM"), but today this is generally considered inappropriate, as it reduces trans men to their medical transitions, whereas "trans man" simply denotes a man who also happens to be trans.
"Are you a girl?"
"No, I'm a trans man, a FTM transsexual."