Other forms: loitering; loitered; loiters
To loiter is to hang around a place with no real purpose, usually somewhere where you are not welcome — like under the “No Loitering” sign at a convenience store.
If you’re a dawdler, or a loafer, then you are probably inclined to loiter from time to time. The verb loiter is similar to “hang out,” but it has a more negative connotation and is sometimes associated with acting illegally. You might hang out at your friend’s house watching movies, but you would loiter by the vending machine at school when you are supposed be in class.