(1) An electronic device which generates a periodic signal of a particular frequency, usually a sine wave, but sometimes a square wave or other waveform. In an analog synthesizer, oscillators typically produce regularly repeating fluctuations in voltage–that is, they oscillate.

(2) In a digital synthesis, an oscillator more typically plays back a complex waveform by reading the numbers in a wavetable. An oscillator allows a choice of pitch and waveform, the first affects the perceived musical pitch and the second affects the timbre. Additional parameters that are almost always found in the oscillator section of a synthesizer are those that deal with vibrato and pitch-bend.