Wiktionary
basic block
n. (context compilers English) A sequence of contiguous instructions that contains no jumps or labels.
Wikipedia
Basic block
In computing, a basic block is a straight-line code sequence with no branches in except to the entry and no branches out except at the exit. This restricted form makes a basic block highly amenable to analysis. Compilers usually decompose programs into their basic blocks as a first step in the analysis process. Basic blocks form the vertices or nodes in a control flow graph.
Usage examples of "basic block".
Granted, this was usually less to do with their design than with the fact that their basic block was so sturdy people would run and run them until they were a liability, and sometimes after that.