From the latin for bruising of the vagina.
A term used when a malefriend gets a scrapped knee or other minor cut from mountain biking, skiing, or other outdoor activity and whinges about it.
Adam: My neck hurts a little.
Dave: Gee adam, maybe you need some homeopathic salve for that labial contusion?
"GL" or "gl" in the manga, manhwa, manhua universe means literally girl's love. Which is a romance genre when both of the main characters are females. Often interpreted as "Yuri" for the Japanese community which means Lily. The fans of the genre are simply called Yuri enthusiast/fan. Another variant for the opposite sex is bl, which you already know it, means boy's love (I'm not into that).
Me: "Hey, did you read the gl manga I recommended you?"
Yurifan: "Oh, Kimi ni Tsumugu Bouhaku? Heck yeah dude, that manga sure be vibin'!"