a flannel Share definition Flag A flannel is a girl who is butch and apears to be a lesbian. They have the stereotype look but may not even be gay. They mistaked her for being gay but it turns out she was just a flannel and she had a boyfriend. a flannel by cisomething April 29, 2015 0 0 Get merch Get the a flannel mug. Buy Now — $32.95 See more merch
