A billion is a number with 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 meaning in both British and American English.
Historically, in British English, 1,000,000,000,000, i.e. one million million, or 1012 (ten to the twelfth power), as defined on the long scale. This is one thousand times larger than the short scale billion, and equivalent to the short scale trillion.American English has always used the short scale definition in living memory but British English once employed both versions. Historically, the United Kingdom used the long scale billion but since 1974 official UK statistics have used the short scale. Since the 1950s the short scale has been increasingly used in technical writing and journalism, although the long scale definition still enjoys some limited usage.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.
Another word for one thousand million is milliard, but this is used much less often in English than billion. Some European languages such as Romanian, Finnish, Georgian, Swedish, Danish, Portuguese, Spanish, Italian, Dutch, Hungarian, Norwegian, Polish, Czech, Slovak, Russian, French, Bulgarian and German, use milliard (or a related word) for the short scale billion, and billion (or a related word) is used for the long scale billion. Thus for these languages billion is thousand times larger than the modern English billion. However, in Russian, milliard (миллиард) is used for the short scale billion, and trillion (триллион) is used for the long scale billion.
The cardinal number 1,000,000: 106; a thousand thousand.
A very large number.
“I told you a million times before.”
a thousand million: 1 followed by nine zeros, 109; a milliard
A million million: a 1 followed by twelve zeros; 1012
A very large number.
“There were billions of people at the concert.”