BLT (blit, very rarely belt) [based on the PDP-10 block transfer instruction; confusing to users of the PDP-11] 1. v. To transfer a large contiguous package of information from one place to another. 2. THE BIG BLT: n. Shuffling operation on the PDP-10 under some operating systems that consumes a significant amount of computer time. 3. (usually pronounced B-L-T) n. Sandwich containing bacon, lettuce, and tomato.