trillionyoudaoicibaDictYouDict[trillion 词源字典]
1680s, from French trillion, from Italian trilione; see tri- + million. In the U.S., the fourth power of a thousand (one thousand billion, 1 followed by 12 zeroes); in Great Britain, the third power of a million (one million billion, 1 followed by 18 zeroes), which is the original sense. Compare billion.[trillion etymology, trillion origin, 英语词源]