Source : Webster's Revised Unabridged Dictionary (1913)

Nonillion \No*nil"lion\, n. [L. nonus ninth + -illion, as in E.
   million.]
   According to the French and American notation, a thousand
   octillions, or a unit with thirty ciphers annexed; according
   to the English notation, a million octillions, or a unit with
   fifty-four ciphers annexed. See the Note under {Numeration}.