The term 'Manx of the House' is a reference to a breed of cats known as Manx cats. These cats are known for their lack of a tail, which is why they are sometimes referred to as 'tailless cats'. The crossword solution for this term is PET, which stands for 'domestic animal'. Manx cats are a popular breed of domestic cats that are known for their intelligence and loyalty. They make great companions and are often kept as pets in households.