- a cardinal number represented in the U.S. by 1 followed by 15 zeros, and in Great Britain by 1 followed by 24 zeros.
- amounting to one quadrillion in number.
Origin of quadrillion
1665–75; quadr- + -illion (as in million)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for quadrillionth
But as this gives something like one thousand quadrillionth part of the density of water, we refuse to accept or even think of it.New Theories in Astronomy
- (in Britain) the number represented as one followed by 24 zeros (10 24)US and Canadian word: septillion
- (in the US and Canada) the number represented as one followed by 15 zeros (10 15)
- amounting to this numbera quadrillion atoms
- (as pronoun)a quadrillion
C17: from French quadrillon, from quadri- + -illion, on the model of million
Word Origin and History for quadrillionth
Online Etymology Dictionary, © 2010 Douglas Harper