Is there a name for quarterhorse and thoroughbred mix?

There isn't a specific, widely recognized name for a Quarter Horse and Thoroughbred mix.

However, you can use some descriptive terms like:

* Quarter Horse/Thoroughbred cross: This is a straightforward and accurate way to describe the mix.

* American Quarter Horse/Thoroughbred cross: This is more specific if you want to emphasize the breed of the Quarter Horse parent.

* Thoroughbred-Quarter Horse mix: This is another straightforward option.

* Hybrid: This term can be used generally to describe any crossbreed.

* Sport horse: This term can be used if the horse is bred for sport, as the mix often results in athletic horses.

Ultimately, the best way to describe the horse depends on the context and what information you want to convey.