compiler, computer software that translates (compiles) source code written in a high-level language (e.g., C++) into a set of machine-language instructions that can be understood by a digital computer’s CPU. Compilers are very large programs, with error-checking and other abilities. Some compilers translate high-level language into an intermediate assembly language, which is then translated (assembled) into machine code by an assembly program or assembler. Other compilers generate machine language directly. The term compiler was coined by American computer scientist Grace Hopper, who designed one of the first compilers in the early 1950s.