billion

from WordNet (r) 3.0 (2006)

billion
    adj 1: denoting a quantity consisting of one thousand million
           items or units in the United States
    2: denoting a quantity consisting of one million million items
       or units in Great Britain
    n 1: the number that is represented as a one followed by 12
         zeros; in the United Kingdom the usage followed in the
         United States is frequently seen [syn: {billion}, {one
         million million}, {1000000000000}]
    2: a very large indefinite number (usually hyperbole); "there
       were millions of flies" [syn: {million}, {billion},
       {trillion}, {zillion}, {jillion}, {gazillion}]
    3: the number that is represented as a one followed by 9 zeros
       [syn: {billion}, {one thousand million}, {1000000000}]

from The Collaborative International Dictionary of English v.0.48

Milliard \Mil`liard"\ (F. m[-e]l`y[.a]r"; E.
   m[i^]l"l[i^]*[aum]rd), n. [F., from mille, mil, thousand, L.
   mille.]
   A thousand millions; -- usually called {billion} in the
   United States. See {Billion}.
   [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Billion \Bil"lion\, n. [F. billion, arbitrarily formed fr. L.
   bis twice, in imitation of million a million. See {Million}.]
   According to the French and American method of numeration, a
   thousand millions, or 1,000,000,000; according to the English
   method, a million millions, or 1,000,000,000,000. See
   {Numeration}.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

19 Moby Thesaurus words for "billion":
      a billion, a crore, a lakh, a million, a myriad, a nonillion,
      a quadrillion, a thousand, a zillion, astronomical number, googol,
      googolplex, infinitude, infinity, jillion, large number, milliard,
      trillion, zillion