oscillator (n.)

1726, intransitive, "to vibrate, move backward and forward," as a pendulum does, a back-formation from oscillation, or else from Latin oscillatus, past participle of oscillare "to swing." Transitive sense of "cause to swing backward and forward" is by 1766. From 1917 in electronics, "cause oscillation in an electric current." Related: Oscillated; oscillating.