| Noun | 1. | gigabyte - a unit of information equal to one billion (1,073,741,824) bytes or 1024 megabytesMB, megabyte - a unit of information equal to one million (1,048,576) bytes terabyte, TB, T - a unit of information equal to a trillion (1,099,511,627,776) bytes or 1024 gigabytes | |