It's a French word (Rendez-vous). I think it's called a "loan" word. Meaning it came from another country and we use it here in our everday language. The word is used just like Nancy said. Example sentence: "We'll rendezvous at the center of the mall when it's time to leave" or you can say: "We'll meet-up at the center of the mall when it's time to leave" Either way works.

It's a meeting, or a date, when you go out or meet with someone.