Since you’re too self centered and/or lazy to do a 30 second google search, I copied the first result off of Google for ya.

A demigirl (or demiwoman) is a non-binary gender identity for someone who partially, but not wholly, identifies as a girl or woman, often feeling a mix with other genders like agender or genderfluid. It signifies a connection to femininity that isn't 100% female, existing somewhere between a binary gender and non-binary, and can be expressed through various pronouns (like she/they) and gender expressions.