billion
n. countablen. the number 1,000,000,000. It is a very large amount, equal to one thousand millions.
n. the cardinal number represented by 1 followed by nine zeros in the short scale system. In modern English usage, it refers to a thousand millions.
The world population is over eight billion people.
The government plans to spend several billion dollars on improving the national rail network over the next decade.
While a million seconds is roughly twelve days, a billion seconds lasts for over thirty-one years, illustrating the vast scale difference between these two numerical orders.
From French billion, equivalent to bi- (“two”) + -illion.
When used as a specific number before a noun, it remains singular ('five billion people'); it becomes plural when used as an indefinite large amount ('billions of stars').
three billions dollarsthree billion dollarsWhen used as a specific quantifier before a noun, the word stays in its singular form.