RPN may refer to: Mathematics Reverse Polish notation, a.k.a. postfix notation, a mathematical notation real projective space Nursing Registered practical nurse, also referred to as a licensed practical nurse Registered psychiatric nurse Other uses Radio Philippines Network, Channel 9, Philippines (National Housing Programme), a type of public housing in Brunei Recherche en Prévision Numérique, a numerical weather prediction research center in Canada Registered Parameter Number, as used in Musical Instrument Digital Interface synthesizers Risk Priority Number, as used in failure mode and effects analysis Rosh Pina Airport (IATA code), Israel