A student, alum, or faculty member of Princeton University. A Princetonian is not to be confused with those people living in and around Princeton Borough and Princeton Township not affiliated with the University; these persons are often referred to as "townies". These townies calling themselves Princetonians is analogous to residents of New Haven calling themselves Yalies: just plain wrong.
Princetonians frequent eating clubs on Thursday and Saturday nights.
A person who attends Princeton University and/or lives in Princeton Township or Princeton Borough in New Jersey.
Forbes is a Princetonian, while Bush is a Yalie.