The Collaborative International Dictionary of English v.0.48:
15 \15\ adj. 1. denoting a quantity consisting of one more than fourteen and one less than sixteen; -- representing the number fifteen as Arabic numerals Syn: fifteen, xv [WordNet 1.5 +PJC]WordNet (r) 3.0 (2006):
15 adj 1: being one more than fourteen [syn: fifteen, 15, xv] n 1: the cardinal number that is the sum of fourteen and one [syn: fifteen, 15, XV]