Adjective. It's usable more between children than adults. It means a human who doesn't want to share.
For example, a child has 1 candy left. We all know, that he/she never will give that last candy to a friend.
- Please give me the candy.
- No, I can't, I have to leave it for my sister at home.
- You don't even have a sister. Griffer!
7👍 3👎