Source : WordNet®

googol
     n : a cardinal number represented as 1 followed by 100 zeros
         (ten raised to the power of a hundred)

Source : Free On-Line Dictionary of Computing

googol
     
         The number represented in base-ten by a one with
        a hundred zeroes after it.
     
        According to Webster's Dictionary, the name was coined in 1938
        by Milton Sirotta, the nine-year-old nephew of American
        mathematician, Edward Kasner.
     
        See also {googolplex}.
     
        (2001-03-29)