Loitering was the act of hanging around in certain places for portracted periods of time. On Earth, it was sometimes frowned upon.
Loitering on Deep Space 9's Promenade was prohibited by station regulation 8-2/7-B. In 2373, an annoyed Nog too offense when Martok and some other Klingons loitered in his and Jake Sisko's favorite place. (DS9: "Blaze of Glory")