1. An acronym for Complementary Metal Oxide Semiconductor. CMOS is a widely used type of semiconductor. CMOS semiconductors use both NMOS (negative polarity) and PMOS (positive polarity) circuits. At any given time, only one of the circuit types is on. Beneficially, CMOS chips require less power than chips using just one type of transistor.
2. A transistor technology. One use of CMOS is for low power memory that stores information about configurations. CMOS technology is very sensitive to static electricity.