What does trillion mean?
A trillion is a cardinal number used for an enormous quantity of something. In the short scale used in the United States and now standard in most contemporary British usage, it equals 10^12, or one million million. Traditional British long-scale usage instead assigned it 10^18, so the same word can have different numerical values depending on the convention. The term is chiefly used in formal discussion of national economies, company finances, scientific quantities, and abstract claims about very large numbers. As a noun, it is normally used after a numeral or as "one trillion," while hyphenated attributive forms such as "trillion-dollar" attach it to a following noun. The word matters because apparent claims about money or scale may depend on which numerical convention the speaker uses. Its memorable history is therefore not merely trivia but a practical guide to interpreting large figures.
nounA cardinal number equal to 10^12, or one million million, in modern American and contemporary British usage. In the traditional British long scale, it denotes 10^18, or a thousand million million.
- In the short scale used in the United States and now standard in British English, one trillion equals 10^12, or one million million.
- In the older British long scale, one trillion equals 10^18, or a thousand million million.
"The project is expected to cost more than one trillion dollars."
"The national debt surpassed one trillion dollars."
"The reaction reached completion in less than a trillionth of a second."
The standard plural is used particularly before "of" to express an indefinitely large number.
"There are trillions of stars in the observable universe."
A trillion can mean two very different numbers: most Americans and contemporary British readers understand it as 10^12, while the traditional British long scale assigns it 10^18.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does trillion come from?
Trillion entered English in the early modern period from French trillion, a formation based on Latin tril- and the numerical suffix -illion, which is ultimately related to Latin mille, meaning "thousand." English subsequently used the word on both the short and long numerical scales. The short scale became standard in the United States and eventually in Britain, while the long-scale value remained common in British usage for much of the twentieth century.
Related word forms
How trillion is actually used
Chiefly used in formal, quantitative contexts involving money, economics, science, or very large abstract quantities. As a modifier before a noun, it is normally hyphenated, as in "a trillion-dollar economy."
Easily confused with trillion
In US and modern British usage, a billion is 10^9 and a trillion is 10^12; under the traditional British long scale, a billion meant 10^12 and a trillion meant 10^18.