1. A measure of how long it takes for a given job or piece of work to be completed, or for a message to make its way from source to destination. See also throughput.
2. The time taken for the start of a given sector of data on a storage disk to reach the read/write head. The time is measured from the instant that the head settles at the track within which the sector lies. The average latency is the time for half a revolution of the disk. See also access time, seek time.