YO-YO strings are the thin strings used to attach a YO-YO to the user's finger. The strings come in different lengths and thicknesses, depending on the type of YO-YO being used. The crossword solutions for the term YO-YO strings are CELLI (5 letters), CELLO (5 letters), and CELLOS (6 letters). CELLI and CELLO are both variations of the same word, which is derived from the Italian word for 'LITTLE'. CELLOS is a plural form of the same word.