The term SPARE PARTS can be broken down into three crossword solutions: NINEPINS (8 letters), PINS (4 letters), and RIBS (4 letters). NINEPINS is a type of bowling game that uses nine pins instead of the traditional ten. PINS are small cylindrical objects used to secure items together, such as in sewing or jewelry making. RIBS are curved bones that form the rib cage and protect the internal organs. All three of these terms can be used to describe SPARE PARTS, which are components or accessories that can be used to replace or supplement existing PARTS.