x87

Etymology
Named after the product designations of the coprocessors used to provide floating-point support on early x86 systems lacking hardware support for these instructions in the main processor: the 8087 (for the 8086/8088 CPU), 80287 (for the 80286 CPU), 80387 (for the 80386 CPU), and 80487SX (for the 80486SX CPU). The 80486DX CPU and later integrated the floating-point hardware into the main processor, but the name continued in use for this set of instructions. The x serves as a wildcard.

Proper noun

 * 1)  An extension to the x86 CPU instruction set architecture, providing direct hardware support for advanced floating-point arithmetic operations (rather than requiring them to be emulated in software).

Coordinate terms

 * 3DNow!
 * 3DNow!