Source : WordNet®

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

Source : Free On-Line Dictionary of Computing

swap file
     
         A file used by a {program} or, more often,
        an {operating system} as {swap space}.  A swap file is usually
        allocated as a long contiguous section of a {hard disk} to
        reduce access time.  The disk space used for a swap file can
        not be used for other things.  Under {Microsoft Windows}, swap
        files are recommended not to exceed three times the available
        {RAM} and are usually 150 percent of the RAM size.
     
        (1996-11-15)