500th
         adj 1: the ordinal number of five hundred in counting order
                  [syn: {five-hundredth}, {500th}]

English Dictionary: 55th	by the DICT Development Group
From WordNet (r) 3.0 (2006) [wn]:
50th adj the ordinal number of fifty in counting order [syn: fiftieth, 50th]
From WordNet (r) 3.0 (2006) [wn]:
55th adj the ordinal number of fifty-five in counting order [syn: fifty-fifth, 55th]
From WordNet (r) 3.0 (2006) [wn]:
5th adj coming next after the fourth and just before the sixth in position Synonym(s): fifth, 5th