| Nonillion (n.) 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 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 | ![]() |