The term 'Blue Ball' can be broken down into TWO crossword solutions: TWO (3 letters) and CATS (4 letters). TWO is an indefinite pronoun that is used to refer to a person, thing, or amount that is not specified. CATS is an acronym for the musical 'CATS' which is a musical composed by Andrew Lloyd Webber based on T.S. Eliot's Old Possum's Book of Practical CATS. The musical tells the story of a tribe of CATS called the Jellicles and the night they make the 'Jellicle Choice' and decide which cat will ascend to the Heaviside Layer.