Prospective students, informally known as prospies, are people who aren't quite Knox yet, but may be in the future. You can spot them by the purple folders they're always carrying around, their accompanying grownups, and that vague, lost look in their eyes as they try to figure out where "George Davis Hall" is.
The Office of Admission doesn't like it when people call them prospies. But sometimes that's hard, because "prospective student" takes a long time to say, especially if you can't remember their names. A possible solution to this problem is to refer to them as "prospectives".