Definitions

1. verb

to respond (especially by mail) to an invitation (such as a wedding or formal event) with a statement of acceptance or regret

“She RSVP’d to the wedding invitation last week, indicating that she and her husband would be attending.”

2. noun

a response to an invitation (such as a wedding or formal event) stating whether one will or will not attend

“The guest list included RSVPs from over 50 people.”