Mental Floss magazine recently reprinted a 2004 article titled 10 Latin Phrases You Pretend to Understand. I plagiarize shamelessly.

Whether you’re deciphering a cryptic state seal or trying to impress your Catholic in-laws, knowing some Latin has its advantages. But the operative word here is “some.” We’ll start you off with 10 phrases that have survived the hatchet men of time (in all their pretentious glory).

persona non grata – an unacceptable person

Remember your old college buddy, the one everybody called Chugger? Now picture him at a debutante ball, and you’ll start to get a sense of someone with persona non grata status. The term is most commonly used in diplomatic circles to indicate that a person is unwelcome due to ideological differences or a breach of trust. Sometimes, the tag refers to a pariah, a ne’er-do-well, a killjoy, or an interloper, but it’s always subjective.