The term 'TREMOLO' is a 7-letter musical effect that produces a trembling or vibrato sound. It is created by rapidly repeating a single note or chord, usually at a constant rate. This effect is commonly used in classical, jazz, and folk music, as well as in some rock and pop genres. The TREMOLO effect can be achieved through the use of an electronic device, such as a pedal, or by manipulating the strings of an instrument.