/ ˈtrɪljən; NAmE / number
1.
1 000 000 000 000; one million million
HELP NOTE : You say a, one, two, several, etc. trillion without a final 's' on 'trillion'. Trillions (of ... ) can be used if there is no number or quantity before it. Always use a plural verb with trillion or trillions .
2.
a trillion or trillions ( informal ) a very large amount
HELP NOTE : There are more examples of how to use numbers at the entry for hundred .
3.
( old-fashioned , BrE ) one million million million; 1 000 000 000 000 000 000
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WORD ORIGIN
late 17th cent.: from French , from million , by substitution of the prefix tri- three for the initial letters.