hound

Hound comes from Middle English hound, from Old English hund, tracing back through Proto-West Germanic *hund and Proto-Germanic *hundaz to Proto-Indo-European *ḱwṓ. It's a doublet of canine, meaning the two words descend from the same ancient root by different paths.

In 14th-century England, hound was simply the general word for any domestic dog, while dog meant something more specific, like a mastiff or bulldog. By the 1500s the two words had swapped roles: dog became the everyday term, and hound narrowed to mean breeds used for hunting.

It's cognate with Dutch hond, German Hund, Danish/Norwegian/Swedish hund, and Icelandic hundur — all still meaning simply 'dog' in their languages, a reminder of what hound itself used to mean in English.