bil·lion 
/ˈbɪljən/ noun
plural billion or bil·lions /ˈbɪljən/ noun [count] 1 : the number 1,000,000,000 : one thousand million
▪ a/one/two billion (of them) ▪ a hundred billion = 100 billion ▪ several billion (of them) = (less commonly) several billions (of them) ▪ hundreds of billions (of them) ▪ a billion and one [=1,000,000,001] ▪ a billion and a half = 1.5 billion [=1,500,000,000] ▪ The company is worth billions. [=worth billions of dollars, pounds, euros, etc.] 2 : a very large amount or number
▪ We could see a billion stars in the sky. ▪ I've heard that excuse a billion times before. [=many, many times before] — often plural ▪ We could see billions of stars. ▪ billions and billions of stars 3 Brit, old-fashioned : the number 1,000,000,000,000 : trillion
▪ a/one/two billion (of them) ▪ a hundred billion = 100 billion ▪ several billion (of them) = (less commonly) several billions (of them) ▪ hundreds of billions (of them) ▪ a billion and one [=1,000,000,001] ▪ a billion and a half = 1.5 billion [=1,500,000,000] ▪ The company is worth billions. [=worth billions of dollars, pounds, euros, etc.]
▪ We could see a billion stars in the sky. ▪ I've heard that excuse a billion times before. [=many, many times before] — often plural ▪ We could see billions of stars. ▪ billions and billions of stars
— bil·lionth /ˈbɪljənθ/ adjective
▪ our (one) billionth customer ▪ This is the billionth time I've seen this show. [=I've seen this show many times]
/ˈbɪljənθ/ adjective ▪ our (one) billionth customer ▪ This is the billionth time I've seen this show. [=I've seen this show many times]
— billionth noun, plural billionths [count]
▪ one billionth [=one of a billion equal parts] of a second
▪ one billionth [=one of a billion equal parts] of a second
