Final answer:
The width of the vibrato refers to the range of notes covered by the pitch variations in the vibrato.
Step-by-step explanation:
The width of the vibrato refers to the range of notes covered by the vibrato. Specifically, it is the extent to which the pitch varies above and below the note being played. The speed of the vibrato, on the other hand, is how quickly these pitch variations occur, while the amplitude would relate to the intensity or loudness of the sound. Finally, the waveform or shape of the vibrato wave doesn't directly correspond to 'width' but can affect the perceived character or timbre of the vibrato.