A trait in someone that's not alarming or attractive, just weird, quirky, or boring in the dating context. It's the gray zone of dating: doesn't make you run like a red flag but doesn't excite you either.

An ugly or unattractive woman. It's a pretty blunt Colombian insult used mostly among men to talk disparagingly about someone's looks. Definitely not something you'd say to someone's face unless you want trouble.

Refusing to share information, places, or recommendations so they don't get popular and get ruined. It's the cultural selfishness of the social media era.

Something cool, awesome, or really well done. In Colombia, when something or someone is melo, it's top quality, the best of the best. Think of it as the Colombian equivalent of saying something is fire or sick.