certain party
An intentionally vague term used to refer to someone without revealing their identity. When I asked Carly how she knew about my new relationship, she just said that a certain party told her, but I'm going to need some specifics eventually! I planned to stop by your house tonight, but a certain party threw a tantrum when I tried to pry him away from his toys.
certain party
someone you know but whom I do not wish to name. I spoke to a certain party about the matter you mentioned. If a certain party finds out about you-know-what, what on earth will you do?