Mutt/mʌt/ Definition 1 of 1Pro Tip 1/3Informal Usage The term 'mutt' is informal and is used more in casual conversation than in formal writing. I adopted a mutt from the shelter; he's so playful! Pro Tip 2/3Not Derogatory 'Mutt' can be endearing and is not generally intended as an insult when describing a dog. My little mutt is part of the family. Pro Tip 3/3Neutral Connotation The word 'mutt' is neutral, but the tone of voice can change its connotation from affectionate to dismissive. Isn't that mutt just adorable?