Rendezvous is a very French way to say "meeting" or "date." So go ahead and call your next dentist appointment or lunch date with friends a rendezvous.
In the 1590s, rendezvous meant “a place for assembling of troops.” And you'll still hear military tacticians talking about "rendezvous points" today. But more often we use rendezvous to describe an assembling of friends, an appointment, or a date with your secret lover. If you're feeling extra Frenchy, you can use rendezvous as a verb, as in "Let's rendezvous next Saturday at the mall."