FtF

FtF (Female-to-Female) is a term for transgender women who consider themselves transitioning from female to female, as they has always been female, just not in the way being female is traditionally defined as. They have always been female and always will be female, regardless of whatever genital, hormonal, or chromosomal arrangements they were born with, and whether they chooses to make changes to their body or not.

It is an alterative to MtF as MtF implies that one was male at some point, then transitioned to female, which does not accurately describe how some trans women view their gender. Male-to-female is a framing that’s easier to explain, but only because it's still rooted in the concept of binary sex distinctions and assuming gender based on sex, which many trans people want to do away with entirely. The male counterpart is MtM