[from BLT, q.v.:]
1. [common] 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. Synonym for blit or BLT. Both uses are borderline techspeak.