The crossword solution for the term 'Mutt and ___' is 'Jeff', which is a four-letter word. The phrase 'Mutt and Jeff' is a popular American idiom that originated in the early 1900s. It is used to describe two people who are very different from each other, usually in terms of their physical characteristics, personalities, or social status. The phrase was derived from a comic strip created by Bud Fisher in 1907, which featured two characters named Mutt and Jeff. Mutt was a tall, thin man, while Jeff was short and stout. The phrase has since been used to refer to any two people who are drastically different from one another.