The term 'RUBBER-OUTER' is a combination of two words, 'RUBBER' and 'ERASER'. The first word, 'RUBBER', refers to a material made from the sap of certain trees that is used to make a variety of products, including tires, hoses, and soles for shoes. The second word, 'ERASER', refers to a tool used to remove pencil or pen marks from paper. Together, the two words form the term 'RUBBER-OUTER', which is used to describe an ERASER made from RUBBER.