The term 'Dog of Dennis the Menace' refers to the pet dog of the character Dennis the Menace, who is a mischievous young boy in the comic strip and television series of the same name. The crossword solution for this term is 'RUFF', which is a four-letter word meaning a loud, gruff sound made by a dog. This is an appropriate description of the Dog of Dennis the Menace, as he is often seen barking and making other loud noises.