Fingender (shortened to FIN) is an umbrella term for all genders which are feminine in nature (FIN). It can be used as an umbrella term for any genders that are primarily related to femininity. Fingenders may or may not also be related to womenhood.
It can also be used as a gender on its own, referring to any gender that isn't fully defined by being feminine but is still related to femininity, or a gender in which femininity is its defining feature but the gender is not binary female. It's often used by people who cannot narrow down their gender any more than being feminine, but still definitely not a binary woman.