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 (ten to the ninth power), as defined on the short scale (also known as a milliard on the long 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. 1,000,000,000,000, i.e. one million million, or (ten to the twelfth power), as defined on the long scale (that is, a trillion in the short 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.

American English adopted the short scale definition from the French (it enjoyed usage in France at the time, alongside the long-scale definition). The United Kingdom used the long scale 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. Moreover, in 1941, Winston Churchill remarked: "For all practical financial purposes a billion represents one thousand millions..."