(1) Billion. Abbreviated "G." It often refers to the precise value 1,073,741,824 since computer specifications are usually binary numbers. See GB, binary values and space/time.

(2) A prefix attached to words that means a very large size or quantity. For example, "gigabucks" means a lot of money. Since giga has become more commonly used in terms such as gigahertz and gigabits, it has become an alternate word for "mega" to describe something very large. See mega.