Mutt is a term used to describe a mixed breed dog. However, there are several synonyms that can be used to refer to such dogs. One of the most commonly used synonyms is "mongrel," which is derived from the Old English word "gemong" meaning mixture. Another synonym is "cur," which is an old-fashioned term used to refer to a mixed-breed dog of low quality. Additionally, the term "Heinz 57" is used to describe a mixed-breed dog, referring to the various types of ingredients in a bottle of ketchup. Other synonyms include "muttley," "scrub," and "street dog." Regardless of the term used, most people agree that mixed-breed dogs make wonderful and loving pets.