• synonyms


[bil-yuh n]
noun, plural bil·lions, (as after a numeral) bil·lion.
  1. a cardinal number represented in the U.S. by 1 followed by 9 zeros, and in Great Britain by 1 followed by 12 zeros.
  2. a very large number: I've told you so billions of times.
Show More
  1. equal in number to a billion.
Show More

Origin of billion

1680–90; < French, equivalent to b(i)- bi-1 + -illion, as in million
Related formsbil·lionth, adjective, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for billionth

Contemporary Examples

Historical Examples

British Dictionary definitions for billionth


noun plural -lions or -lion
  1. one thousand million: it is written as 1 000 000 000 or 10 9
  2. (formerly, in Britain) one million million: it is written as 1 000 000 000 000 or 10 12
  3. (often plural) any exceptionally large number
Show More
  1. (preceded by a or a cardinal number)
    1. amounting to a billionit seems like a billion years ago
    2. (as pronoun)we have a billion here
Show More
Derived Formsbillionth, adjective, noun

Word Origin

C17: from French, from bi- 1 + -llion as in million
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for billionth

1778, from billion + -th (2).

Show More



1680s, from French billion (originally byllion in Chuquet's unpublished "Le Triparty en la Science des Nombres," 1484; copied by De la Roche, 1520), from bi- "two" (see bi-) + (m)illion. A million million in Britain and Germany (numeration by groups of sixes), which was the original sense; subsequently altered in French to "a thousand million" (numeration by groups of threes) and picked up in that form in U.S., "due in part to French influence after the Revolutionary War" [David E. Smith, "History of Mathematics," 1925]. France then reverted to the original meaning in 1948. British usage is truer to the etymology, but U.S. sense is said to be increasingly common there in technical writing.

Show More
Online Etymology Dictionary, © 2010 Douglas Harper