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From The Collaborative International Dictionary of English v.0.48:
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. [1913 Webster]