In the English language, an RSVP is a response to an invitation. It is an acronym. Even though the letters are pronounced individually, it is a word that is made up by the initial letters of a set of words.
        RSVP stands for "repondez s'il vous plait" which translates in English to "answer please." This is a term that we have taken from the French language and it is therefore an example of borrowing.  Not only did we borrow this word, but we have managed to change the definition from its french translation to an english translation which is,  "respond so very promptly."
       We have also managed to change the function of RSVP, which was originally used as a verb. For example, "Please RSVP by May 23rd" is requesting an action. However it has become acceptable to say "Please send in your RSVP by May 23rd", referring to an RSVP as a physical object. This is an example of conversion.
       RSVP was originally inserted in writing only, however it is now used in verbal speech as well.  It has undergone a number of transformations and it is very possible that it will continue to evolve. For instance, it is a four syllable, fairly difficult term to pronounce. If it were not written as an acronym, it would look something like, "Aressveapea." In other words, this word has potential for growth because it could be made easier to write or say by clipping.