trillion

The cardinal number equal to 10¹².

The cardinal number equal to 10¹⁸.

In the original and most systematic sense, sometimes called English numeration, though of Italian origin, the third power of a million

a million of millions of millions; in the French numeration, usual in the United States, a thousand billions, or a million millions.

According to the French notation, which is used upon the Continent generally and in the United States, the number expressed by a unit with twelve ciphers annexed; a million millions; according to the English notation, the number produced by involving a million to the third power, or the number represented by a unit with eighteen ciphers annexed. See the Note under numeration.

A million million: 1 followed by twelve zeros, 1012.

A million million million: 1 followed by eighteen zeros, 1018.

one quintillion in Great Britain

the number that is represented as a one followed by 18 zeros

the number that is represented as a one followed by 12 zeros