quadrillion UK /kwɒˈdɹɪl.jən/US /kwɑˈdɹɪl.i.ən/number 2noun 1forms 1 number2 •A thousand trillion (logic: 1,000 × 1,000⁴): 1 followed by fifteen zeros, 10¹⁵.Integrating data from all continents and major biomes, we conservatively estimate 20 × 10¹⁵ (20 quadrillion) ants on Earth, with a total biomass of 12 megatons of dry carbon. — 2022 •(UK, old-fashioned) A million trillion (logic: 1,000,000⁴): 1 followed by twenty-four zeros, 10²⁴. noun1 •(slang, figurative) Any very large number, exceeding normal description.They'd never understand — not in a quadrillion years. — 1999 formsquadrillions
