billion

the number that is represented as a one followed by 12 zeros; in the United Kingdom the usage followed in the United States is frequently seen

a very large indefinite number (usually hyperbole); "there were millions of flies"

the number that is represented as a one followed by 9 zeros

denoting a quantity consisting of one thousand million items or units in the United States

denoting a quantity consisting of one million million items or units in Great Britain