What is the name for a dog on a chain? - briefly
A dog on a chain is commonly referred to as a "tethered" or "chained" dog.
What is the name for a dog on a chain? - in detail
The term commonly used for a dog that is kept on a chain or leash is "chained dog" or "tethered dog." This description is straightforward and universally understood, reflecting the practice of restricting a dog's movement with a physical restraint such as a chain or rope. The phrase underscores the primary method of control used to maintain the dog's confinement, emphasizing the bond between the animal and its tether. In some regions, specific colloquialisms or local dialects might refer to these dogs differently, but "chained dog" remains the most widely recognized and accepted term in English.