When your heterosexual male friend prioritizes banging his new girlfriend over of hanging outwith the boys. Platonically, we refer to this as gay.
Jimmy has a new girlfriend so he's all about being gay now instead of hanging outwith the boys. Maybe one day he'll be hetero again and decide to hang out with us. The bath house won't be the same without him.
A Man who would rather to date another Man. The term "Gay" can also be used for Woman. Or it could in completely different words be used as being Happy. Also part of the LGBTQ+ community.