noun 1.a cardinal number represented in the U.S. by 1 followed by 27 zeros, and in Great Britain by 1 followed by 48 zeros.
adjective 2.amounting to one octillion in number.
Origin: 1680–90; <
French, equivalent to
oct- oct- +
-illion, as in
million Related forms oc·til·lionth, noun, adjective