The Collaborative International Dictionary of English v.0.48:

19 \19\ adj.
   1. one more than eighteen; denoting a quantity consisting of
      one more than eighteen and one less than twenty; --
      representing the number nineteen as Arabic numerals

   Syn: nineteen, xix
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

19
    adj 1: being one more than eighteen [syn: nineteen, 19,
           xix]
    n 1: the cardinal number that is the sum of eighteen and one
         [syn: nineteen, 19, XIX]