Source : Free On-Line Dictionary of Computing

bitblt
     
        /bit'blit/ [{BLT}] 1. Any of a family of closely related
        algorithms for moving and copying rectangles of bits between
        main and display memory on a {bit-mapped} device, or between
        two areas of either main or display memory (the requirement to
        do the {Right Thing} in the case of overlapping source and
        destination rectangles is what makes BitBlt tricky).
     
        2. {blit}, {BLT}.
     
        [{Jargon File}]