The Collaborative International Dictionary of English v.0.48:

9 \9\ adj.
   1. one more than eight and one less than ten; denoting a
      quantity consisting of nine items or units; --
      representing the number nine as an Arabic numeral.

   Syn: nine, ix
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

9
    adj 1: denoting a quantity consisting of one more than eight and
           one less than ten [syn: nine, 9, ix]
    n 1: the cardinal number that is the sum of eight and one [syn:
         nine, 9, IX, niner, Nina from Carolina, ennead]