dog

How did man’s best friend fetch the name dog? This is actually one of English’s toughest headscratchers.

While dog is an extremely common word, its origin hounds us. Until around the 1500s, the go-to term for dog, was hund, which developed into hound. Fun fact: the Latin word for dog, canis, is the origin of the word canine and is, in fact, etymologically related to hound.

But scholars can’t quite put their paws on where the word dog came from. All we know is that it comes from the rare Old English word docga. But where did this word dog come from? Theories have been offered, but etymologists are left chasing their tails. As it happens, the Spanish word for dog, perro, is also of obscure origin.

So, we guess we’ll let this sleeping dog lie for now.

Dog isn’t alone: it finds lots of company in other English words that seem simple but whose origins are not. Discover more in our slideshow “‘Dog,’ ‘Boy,’ And Other Words That We Don’t Know Where They Came From.”

There is a good reason that a dog is considered man’s best friend: it’s believed humans domesticated dogs over 10,000 years ago and have been part of our lives ever since. Dogs split off from their genetic cousins, wolves, tens of thousands of years ago, but you can see that some dogs have kept the family resemblance. The word dog is a collective name for the species Canis familiaris, of which there are nearly 200 breeds that range from dalmatians to pugs.

There are also numerous, metaphorical ways you can use the English word dog. It can be used to describe a regular person (a lucky dog), a loathsome man (a dirty dog), or even your feet (my dogs are sore). There are plenty more idioms and other expressions that use dog, such as you can’t teach an old dog new tricks, or that reference the behavior of dogs as in bite the hand that feeds you.