We always thought this would make a great name for Aunt Elma's toy poodle, but she doesn't see it that way.
In the financial and legal world (and, uh, in French), pari-passu means "on equal footing": two investments, sides of a deal, or parties are treated equally; there is no preferential treatment.
In a bankruptcy, sometimes it's said that the creditors are treated pari-passu: each of them have the same rights to get repaid, no one has a better crack at getting his or her money back.