numerical control definition by American Heritage Dictionary
numerical control - Computer Definition
A category of automated machine tools, such as drills and lathes, that operate from instructions in a program. Numerical control (NC) machines are used in manufacturing tasks, such as milling, turning, punching and drilling. Both NC and CNC (computerized NC) are used to describe this category. First-generation machines were hardwired to perform specific tasks or programmed in a very low-level machine language. Today, they are controlled by microprocessors and are programmed in high-level languages, such as APT and COMPACT II, which automatically generate the tool path (physical motions required to perform the operation). The term was coined in the 1950s when the instructions to the tool were numeric codes. Just like the computer industry, symbolic languages were soon developed, but the original term remained.