Acronym for metal oxide semiconductor field-effect transistor. A type of field-effect transistor that has an insulating layer of oxide, usually silicon dioxide, separating the gate from the drain-source conduction channel in the semiconductor. In an NMOS the channel is formed between n-type source and drain by negative charge carriers (i.e. electrons). In a PMOS the channel is formed between p-type source and drain by positive charge carriers (i.e. holes).
MOSFETs require no gate input current, other than a pulse to charge or discharge their input capacitance. They can operate at higher switching speeds and lower currents than bipolar transistors.