| Octillion (n.) According to the French method of numeration (which method is followed also in the United States) the number expressed by a unit with twenty-seven ciphers annexed. According to the English method, the number expressed by a unit with forty-eight ciphers annexed. See Numeration. Thesaurus Entries astronomical number, billion, decillion, duodecillion, googolplex, infinitude, infinity, jillion, large number, nonillion, novemdecillion, octillion, octodecillion, quadrillion, quattuordecillion, quindecillion, quintillion, septillion, sexdecillion, sextillion, tredecillion, trillion, undecillion, vigintillion, zillion |