Source : WordNet®

fragmentation
     n 1: separating something into fine particles [syn: {atomization},
           {atomisation}]
     2: the disintegration of social norms governing behavior and
        thought and social relationships
     3: (computer science) the condition of a file that is broken up
        and stored in many different locations on a magnetic disk;
        "fragmentation slows system performance because it takes
        extra time to locate and assemble the parts of the
        fragmented file"
     4: the scattering of bomb fragments after the bomb explodes

Source : Free On-Line Dictionary of Computing

fragmentation
     
        1.  {segmentation}.
     
        2. The process, or result, of splitting a large area of free
        memory (on disk or in main memory) into smaller non-contiguous
        blocks.  This happens after many blocks have been allocated
        and freed.  For example, if there is 3 kilobytes of free space
        and two 1k blocks are allocated and then the first one (at the
        lowest address) is freed, then there will be 2k of free space
        split between the two 1k blocks.  The maximum size block that
        could then be allocated would be 1k, even though there was 2k
        free.  The solution is to "compact" the free space by moving
        the allocated blocks to one end (and thus the free space to
        the other).  See {garbage collection}.