same as oppa. the word noona or nuna is used when a younger guy calls an older girl. its usually use
same as oppa. the word noona or nuna is used when a younger guy calls an older girl. its usually used when its your sister (if you are a guy) but a lot of guys use it when they meet an older girl or if they are friends. its weird to call someone noona when you JUST MET. -- source link