trem·o·lo / ˈtreməˌlō/ • n. (pl. -los) Mus. a wavering effect in a musical tone, typically produced by rapid reiteration of a note, or sometimes by rapid repeated variation in the pitch of a note or by sounding two notes of slightly different pitches to produce prominent overtones. Compare with vibrato. ∎  a mechanism in an organ producing such an effect. ∎  (also tremolo arm) a lever on an electric guitar, used to produce such an effect.

tremolo (It.). Shaking, trembling. In playing of str. instr., the rapid reiteration of a note or chord by back-and-forth strokes of the bow; also, on other instr. as well as str., the very rapid alternation between 2 notes. Note that tremolo is the rapid iteration or alternation of notes, whereas vibrato is fluctuation of pitch.