From Longman Dictionary of Contemporary Englishquadrillionqua‧dril‧lion /kwɒˈdrɪljən $ kwɑː-/ number 1 HMNthe number one followed by 15 zeros2 British English old useHMN the number one followed by 24 zeros
Examples from the Corpus
quadrillion• Sophisticated analysis today can identify traces of pesticides and other substances down to a level of parts per quadrillion.• What are the prospects on the Caricom market for another quadrillion metric tons of sweet potatoes, eh?• To do this systematically would require a computer to examine a quadrillion possibilities.Origin quadrillion (1600-1700) quadr- + -illion (as in million) 