RSVP is an abbreviation that stands for "repondez s'il vous plaît" in French, which means "please respond" in English. There are several synonyms for this word that can be used interchangeably to convey the same message. One common alternative is "kindly respond" or "please reply," which is often used in formal invitations. Another option is "respond by," which specifies a deadline for the recipient to send their response by. "Let us know if you can attend" is a more casual and friendly alternative, while "regrets only" indicates that guests should only respond if they are unable to attend. In any case, the importance of responding to invitations promptly and courteously cannot be overstated.