Source : Webster's Revised Unabridged Dictionary (1913)

Octillion \Oc*til"lion\, n. [L. octo eight + -illion, as in E.
   million: cf. F. octillion.]
   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}.