RSVP is an acronym for the French phrase 'Repondez s'il vous plaît, ' which translates to 'PLEASE respond.' The two crossword solutions, VOUS and SIL, are both part of the phrase. VOUS is the French word for 'YOU, ' while SIL is a contraction of the phrase 's'il vous plaît, ' which means 'PLEASE.' Therefore, the two solutions together form the phrase 'Repondez s'il vous plaît, ' which is the basis for the term RSVP.