this is a real thing https://dictionaryblog.cambridge.org/2012/01/30/gender-benders/

> Girl itself evolved in much the same way. The word originally referred to a child of either sex. Back then, prior to the sixteenth century, girls generally were divided into knave girls, which were boys, and gay girls, which were female girls.

EDIT: I added context, because it may have sounded like I was joking originally. It really is a really thing. boys used to be knave girls and girls used to be gay girls