- prefix one thousand million, or 109.
- A metric prefix representing 109, which is equal to a billion. For instance, 1 gigahertz is equal to 109 Hz. When referring to binary quantities, such bits and bytes, it is equal to 230, or 1,073,741,824, although this is frequently rounded to a billion. To avoid any confusion, the prefix glbi- may be used when dealing with binary quantities. Its abbreviation is G.