Stands for "Complex Instruction Set Computing." This is a type of microprocessor design. The CISC architecture contains a large set of computer instructions that range from very simple to very complex and specialized. Though the design was intended to compute complex instructions in the most efficient way, it was later found that many small, short instructions could compute complex instructions more efficiently. This led to a design called Reduced Instruction Set Computing (RISC), which is now the other major kind of microprocessor architecture. Intel Pentium processors are mainly CISC-based, with some RISC facilities built into them, whereas the PowerPC processors are completely RISC-based.