Loitering was the act of remaining in certain places for protracted periods of time. On Earth, it was sometimes frowned upon and occasionally lead to criminal charges.
Loitering on Deep Space 9's Promenade was prohibited by station regulation 8-2/7-B. In 2373, an annoyed Nog took offense when Martok and some other Klingons loitered in his and Jake Sisko's favorite place. (DS9: "Blaze of Glory")
After Kira Nerys became frustrated with members of the Pah-wraith cult for gathering on the Promenade for three days in 2375, Odo offered to charge them with loitering. She declined, saying she didn't think it would do much good. (DS9: "Image in the Sand")