[1] : The Collaborative International Dictionary of English v.0.48

14 \14\ adj.
   1. denoting a quantity consisting of one more than thirteen
      and one less than fifteen; -- representing the number
      fourteen as arabic numerals

   syn: fourteen, xiv
        wordnet 1.5 +pjc

[2] : WordNet (r) 2.0

14
     adj : being one more than thirteen syn: fourteen, xiv
     n : the cardinal number that is the sum of thirteen and one
         syn: fourteen, xiv
see also:
fourteen xiv xiv 

Carbon 14 >> C Words
Carbon 14, definition of term: Carbon 14
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