Source : Free On-Line Dictionary of Computing

virtual address
     
        1.  A memory location accessed by an
        {application program} in a system with {virtual memory} such
        that intervening hardware and/or software maps the virtual
        address to real ({physical}) memory.  During the course of
        execution of an application, the same virtual address may be
        mapped to many different {physical addresses} as data and
        programs are {paged out} and {paged in} to other locations.
     
        2. In {IBM}'s {VM} {operating system}, {Virtual Device
        Location}.
     
        (2001-01-02)