verb (used without object), RSVPed or RSVP'd, RSVPing or RSVP'ing.
noun, plural RSVP's.
Origin of RSVP
Word Origin for RSVP
also RSVP, c.1845, from French initialism of répondez, s'il vous plait "reply, if you please," as it might have been written on a letter or envelope.
Please reply or answer. From the French, “répondez s'il vous plaît,” meaning “respond if you please.”