math coprocessor: Definition and Much More from Answers.com

(nü¦mer·ik ′prä′ses·ər ik′sten·chən)

(computer science) A specialized integrated circuit that is added to a computer to perform high-speed floating-point mathematical calculations. Abbreviated NPX. Also known as arithmetic processor; math coprocessor; numeric coprocessor.

A mathematical circuit that performs high-speed floating point operations. It is generally built into the CPU chip; however, in older PCs, such as the 386 and 486SX, the math coprocessor was an optional, separate chip. Floating point capability is very important to computation-intensive CAD work, and many CAD programs will not operate without it. A spreadsheet may use it if available, but it is not mandatory. See array processor and vector processor.