since 1979 (earliest usage recorded on this site was 1981)
The Intel 8088 and 8086 CPUs were 16-bit CPUs that first had an instruction set that is now commonly referred to as x86, they were an evolution of the previous generation of 8-bit CPUs such as the 8080, inheriting many characteristics and instructions, extended for the 16-bit era. The 8088 and 8086 both used a 20-bit address bus and 16-bit internal registers but whilst the 8086 had a 16-bit data bus, the 8088, intended as a low cost option for embedded applications, had an 8-bit data bus. The x86 assembly language covers the many different versions of CPUs that followed, from Intel; the 80188, 80186, 80286, 80386, 80486, Pentium as well as non-Intel CPUs from AMD and Cyrix such as the 5x86 and K6 processors. The term x86 applies to any CPU which can run the original assembly language (usually it will run at least some of the extensions too).