Billion

Billion is a word for a large number, and it has two distinct definitions:

• 1,000,000,000, i.e. one thousand million, or 10⁹ (ten to the ninth power), as defined on the short scale. This is now the most common sense of the word in all varieties of English; it has long been established in American English and has since become common in Britain and other English-speaking countries as well.^[1][2][3]
• 1,000,000,000,000, i.e. one million million, or 10¹² (ten to the twelfth power), as defined on the long scale. This number is the historical sense of the word and remains the established sense of the word in other European languages. Though displaced by the short scale definition relatively early in US English, it remained the most common sense of the word in Britain until the 1950s and still remains in occasional use there.^[3]

American English adopted the short scale definition from the French (it enjoyed usage in France at the time, alongside the long-scale definition).^[4] The United Kingdom used the long scale billion until 1974, when the government officially switched to the short scale, but since the 1950s the short scale had already been increasingly used in technical writing and journalism.^[5]

Other countries use the word billion (or words cognate to it) to denote either the long scale or short scale billion. (For details, see Long and short scales § Current usage.)

Milliard, another term for one thousand million, is extremely rare in English, but words similar to it are very common in other European languages.^[6][7] For example, Bulgarian, Catalan, Croatian, Czech, Danish, Dutch, Finnish, French, Georgian, German, Hebrew (Asia), Hungarian, Italian, Kazakh, Kyrgyz, Lithuanian, Luxembourgish, Norwegian, Persian, Polish, Portuguese (although the expression mil milhões — a thousand million — is far more common), Romanian, Russian, Serbo-Croatian, Slovak, Slovene, Spanish (although the expression mil millones — a thousand million — is far more common), Swedish, Tajik, Turkish, Ukrainian and Uzbek — use milliard, or a related word, for the short scale billion, and billion (or a related word) for the long scale billion. Thus for these languages billion is a thousand times larger than the modern English billion.