The Collaborative International Dictionary of English v.0.48:

24 \24\ adj.
   1. one more than twenty-three; denoting a quantity consisting
      of twenty-four items or units; -- representing the number
      twenty-four as Arabic numerals

   Syn: twenty-four, xxiv
        [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

24
    adj 1: being four more than twenty [syn: twenty-four, 24,
           xxiv]
    n 1: the cardinal number that is the sum of twenty-three and one
         [syn: twenty-four, 24, XXIV, two dozen]