1670s, from French quadrillion (16c.) from quadri- "four" (see quadri-) + (m)illion. Compare 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).
英英释意
1. the number that is represented as a one followed by 24 zeros;
"in England they call a septillion a quadrillion"
2. the number that is represented as a one followed by 15 zeros
