Seek time is a delay associated with reading or writing data on a computer's disk drive. In order to read or write data on a particular place on the disk the read/write head of the disk needs to be moved to the correct place (just as to play a particular song on a cassette of recorded music the tape needs to be wound to the right place). This process is known as "seeking" and the time it takes for the head to move to the right place is the "seek time". Usually one is interested in the average seek time.
In 2001 a typical seek time for a hard disk might be 6ms. Floppy disks usually have much longer seek times than hard disks.