SIMD - technical definition

(Single Instruction stream Multiple Data stream) A computer that performs one operation on multiple sets of data. It is typically used to add or multiply eight or more sets of numbers at the same time for multimedia encoding and rendering as well as scientific applications. Hardware registers are loaded with numbers, and the mathematical operation is performed on all registers simultaneously.

SIMD capability was added to the Pentium CPU starting with the Pentium MMX chip and enhanced in subsequent Pentiums (see MMX and SSE). Array processors are machines specialized for SIMD operations (see array processor).