Girlish is an umbrella term for any sort of female-aligned, woman-aligned, girl-aligned, or feminine-aligned gender, and it was made as an easy-to-understand alternative to labels such as fingender, fegender, and fiaspec.
Girlish can also be an identity on its own for one who feels like they are sort of a girl, not quite a girl, not fully a girl, almost a girl, a little bit of a girl, or any other sort of variation of that could be described as girlish. The boy version is boyish.
The flag was created on February 26, 2021, by FANDOM user RoseWatera. The duller pink on the flag represents the way girlish people may be sort of, but not fully, a girl. The purple represents femininity, masculinity, and the mixing of the two, and the white stripe represents the union of all identities that could be considered 'girlish,' just as white is a mixture of all colors.