Fido is a common noun that refers to a dog. However, there are countless synonyms to describe man's best friend. Some of the most popular synonyms for Fido are pup, pooch, canine, hound, mongrel, mutt, and four-legged friend. Other terms that people use to refer to their furry companions include bow-wow, pet, doggie, doggo, and woof-woof. These terms carry different connotations and may be used interchangeably based on the context, the breed of the dog, and the relationship between the dog and its owner. Whatever term one chooses to use, they all reflect the special bond that exists between humans and their loyal companion, the dog.