Synthesizer: (Often shortened to synth.) A device driven by a microprocessor, which contains a programmable chip. Examples of instruments that can control synthesizers: Guitar, keyboard, wind, string, drum controllers. The keyboard itself does not produce musical sound. A synthesizer circuit, built into the keyboard, accomplishes this function. Originally, a synthesizer was so called because it synthesized acoustic instruments. Today, the term refers to the sound-generating circuitry of any MIDI gear. Another term is sound module.

A synthesizer is capable of generating sound using real-time control over the key parameters of sound: frequency, timbre, amplitude, and duration and may refer to an internal sound card or external box for use with multimedia sequencing software.