A mare who is attracted to other mares.
Rainbow Dash is very likely a fillyfooler.
by A_Random_Brony April 17, 2011
Commonly used in My Little Pony: Friendship is Magic fanfictions. A Filly Fooler is a pony that is attracted to the same gender.
In FlutterDash shippings Rainbow Dash and Fluttershy are depicted as Filly Foolers
by EpicDash377 March 02, 2015