Source : WordNet®

swap space
     n : the disk space that is set aside for virtual memory [syn: {swap
         file}]

Source : Free On-Line Dictionary of Computing

swap space
     
         An area of disk (e.g. a {swap file}) used
        to store the state of a process that has been {swap}ped out.
        Under a {virtual memory} system, it is the amount of swap
        space rather than the amount of {physical memory} which
        determines the maximum size of a single process and the
        maximum total size of all active processes.
     
        [{Jargon File}]
     
        (1994-11-03)