The term 'Do, Re or Mi' is a reference to the musical notes of the same name. Do, Re and Mi are the first three notes of the musical scale and are often used as a starting point for teaching music theory. The crossword solutions for this term are 'NOTE' (4 letters) and 'TONE' (4 letters). A NOTE is a musical sound that can be written down and played back, while a TONE is the quality of a sound that distinguishes it from other sounds.