15 15 /ˈfɪfˈtin/

adjective

1. () Being one more than fourteen  ( xv , fifteen , 15 )
   being one more than fourteen
     The fifteen-year-old girl performed a beautiful dance routine.
   The fifteen-year-old girl performed a beautiful dance routine.
   

noun

1. () The cardinal number that is the sum of fourteen and one  ( XV , fifteen , 15 )
   the cardinal number that is the sum of fourteen and one
    I remember my fifteenth birthday party like it was yesterday
   I remember my fifteenth birthday party like it was yesterday