It references an entire aesthetic, often including multicolored hair, makeup such as blush and eyeliner, chokers, among other things. Including, yes, cat ears at times. The male equivalent is "e-boy". You can likely just google if you'd like a more filling description.

They really like those (yuumei inspired) cat ear headphones too.
E Girls wanna be cats...idk...it's weird.
Good lora though, if you want that.

@SL0TWRX What makes you think they want to be a cat just because they pick a cute attribute from a cat? Swimmers use shark-skin inspired fabric for swimwear, does that mean that swimmers actually want to be sharks?

@escheresque Since no one else answered your question, yes, swimmers actually want to be sharks. Hard to believe, but true!

@Desync Thats unfortunate but understandable. Could yiu maybe share some insights where and how you collected your training data?