15(n = noun.quantity) fifteen, xv - the cardinal number that is the sum of fourteen and one;
is a kind of large integer

   15(s = adj.all) fifteen, xv - being one more than fourteen;

   denoting a quantity consisting of one more than fourteen and one less than sixteen; -- representing the number fifteen as Arabic numerals [WordNet 1.5]

15 august 1945, 15 may organization, 15 minutes, atomic number 15, august 15