RSVP
RSVP is actually a French abbreviation for "Répondez s'il vous plaît" which in English is "respond please."
I would super appreciate if you would let us know if you're coming or not - it really helps with the expected amount of food we have to get ready. If you're not gonna eat, I guess I can't make you RSVP - but I'll be watching the desert table for people on my "Didn't-RSVP-naughty-list."