Толковый словарь английского языка Oxford English Reference - billion

n. & adj. --n. (pl. same or (in sense 3) billions) (in sing. prec. by a or one) 1 a thousand million (1,000,000,000 or 10(9)). 2 (now less often, esp. Brit.) a million million (1,000,000,000,000 or 10(12)). 3 (in pl.) colloq. a very large number (billions of years). --adj. that amount to a billion. Derivatives billionth adj. & n. Etymology: F (as BI-, MILLION)