[1] : WordNet (r) 2.0

zillion
     adj : very large indeterminate number; "a zillion people were
           there" syn: a zillion
see also:
a zillion 

[2] : Moby Thesaurus II by Grady Ward, 1.0

52 moby thesaurus words for "zillion":
   a billion, a crore, a lakh, a million, a myriad, a nonillion,
   a quadrillion, a thousand, a zillion, astronomical number, billion,
   considerable, decillion, duodecillion, ever so many, full many,
   googol, googolplex, heaped-up, infinitude, infinity, jillion,
   large number, many, million, multifarious, multifold, multiple,
   multitudinal, multitudinous, myriad, no few, nonillion, not a few,
   novemdecillion, numerous, octillion, octodecillion, quadrillion,
   quattuordecillion, quindecillion, quintillion, quite some,
   septillion, sexdecillion, sextillion, thousand, tredecillion,
   trillion, undecillion, very many, vigintillion

Zillion >> Z Words
Zillion, definition of term: Zillion
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