What does dog mean?
A dog is a domesticated member of the family Canidae, descended from ancient wolves and shaped by millennia of selective breeding into hundreds of distinct breeds ranging from the tiny Chihuahua to the towering Great Dane. Dogs serve humans as companions, guards, herders, hunters, and assistance animals, and their long cohabitation with people has made them among the most culturally significant animals in history. Beyond its literal meaning, the word carries rich figurative weight: to be dogged is to be persistently pursued or characterised by stubborn determination, while calling something a dog informally suggests it is of poor quality. Idioms abound — a dog's life, the dog days of summer, letting sleeping dogs lie — reflecting how deeply embedded the animal is in everyday English. The word itself has a curious history: it emerged in late Old English of uncertain origin and gradually displaced the older term hound, which survives today chiefly for hunting breeds.
A domesticated carnivorous mammal (Canis familiaris) bred into many varieties and kept as a companion, worker, or pet.
"The border collie is widely regarded as one of the most intelligent dogs."
In informal usage, "dog" can also mean a worthless person or a failure ("the film was a real dog").
To follow or pursue someone persistently, especially in a way that causes discomfort or distress.
"Doubts about the data continued to dog the researchers for years."
Often used figuratively with abstract subjects such as problems, rumours, or guilt.
The plural follows the regular English pattern of adding -s.
"Three dogs were playing fetch in the park."
The word "dog" appears nowhere in Old English — it was such a mystery word that its ultimate origin is still unknown, yet it completely replaced the older word "hund" within a few centuries.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dog
The word "dog" first appears in late Old English as "docga", a rare term of unknown origin that referred to a powerful breed of canine. Over the following centuries it steadily displaced the native Germanic word "hund", which had been the general term for a dog. The ultimate etymology remains genuinely uncertain — no secure cognates exist in other Indo-European languages, making "dog" one of the more mysterious common English words.
Related word forms
How dog is actually used
As a noun, "dog" is neutral in most contexts, though informal senses can carry negative connotations (an unattractive person, something shoddy, or in some dialects a friend, as in Australian slang "you old dog"). The plural "dogs" is standard with no irregular form.
Easily confused with dog
"Doc" is an informal term for a doctor, while a "dog" is a domesticated canine animal.