• synonyms


[ sep-til-yuh n ]
/ sɛpˈtɪl yən /

noun, plural sep·til·lions, (as after a numeral) sep·til·lion.

a cardinal number represented in the U.S. by 1 followed by 24 zeros, and in Great Britain by 1 followed by 42 zeros.


amounting to one septillion in number.

Nearby words

septicity, septico-, septicopyemia, septifragal, septilateral, septillion, septimal, septimana, septime, septimus, septisyllable

Origin of septillion

1680–90; < French, equivalent to sept seven + -illion, as in million
Related formssep·til·lionth, noun, adjective Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for septillion


/ (sɛpˈtɪljən) /

noun plural -lions or -lion

(in Britain, France, and Germany) the number represented as one followed by 42 zeros (10 42)
(in the US and Canada) the number represented as one followed by 24 zeros (10 24)Brit word: quadrillion
Derived Formsseptillionth, adjective, noun

Word Origin for septillion

C17: from French, from sept seven + -illion, on the model of million
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for septillion



1680s, from sept- (see septi-) + (m)illion. Cf. billion.

Online Etymology Dictionary, © 2010 Douglas Harper