Male to Female
From BDSM Wiki
A person who was assigned the binary gender of male at birth but who identifies as female.
A MtF identifying person may or may not have started hormones or surgeries. A person may not wish to undergo the procedures, as they are comfortable in their current body, despite their gender identity. This does not mean they do not identify as a female or that they should be treated as a male.
Proper communication etiquette says to use their preferred pronouns and to refer to them as a female.