The Collaborative International Dictionary of English v.0.48:

16 \16\ adj.
   Denoting a quantity consisting of one more than fifteen and
   one less than seventeen; -- representing the number sixteen
   as Arabic numerals

   Syn: sixteen, xvi
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

16
    adj 1: being one more than fifteen [syn: sixteen, 16, xvi]
    n 1: the cardinal number that is the sum of fifteen and one
         [syn: sixteen, 16, XVI]