**Tril"lion** (?), n. [F. *trillion*, formed from the pref. *tri-* in imitation of *million* a million. Cf. Billion.]

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.

© Webster 1913.