noun, plural quad·ril·lions, (as after a numeral) quad·ril·lion.
- quadripedal extensor reflex,
Origin of quadrillion
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|Willam Stirling
- amounting to this numbera quadrillion atoms
- (as pronoun)a quadrillion
Word Origin for quadrillion
1670s, from French quadrillion (16c.) from quadri- "four" (see quadri-) + (m)illion. Cf. billion. In Great Britain, the fourth power of a million (1 followed by 24 zeroes); in the U.S., the fifth power of a thousand (1 followed by 15 zeroes).