R.S.V.P.

'R.S.V.P.' is French for 'Réponde, s'il vous plaît,' which means literally, 'Respond, if it pleases you.' You will see this at the bottom of a formal invitation, such as to a black-tie event or a wedding. Because sometimes people are not good about responding, now you will sometimes see 'Regrets only,' which means you only have to reply if you can't come. Each letter is pronounced separately, not as one word.

Example:
-Did you R.S.V.P. for your cousin's wedding?
-Yes, I mailed it yesterday.