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.
in England they call a quintillion a trillion
in England they call a trillion a billion
trilateral
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trilemma
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trill
trillion
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trillium
trilobite
trilogy
trim
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