Is a mule a horse or a donkey?

A mule is fathered by a male donkey and a female horse. And there is
another permutation, a hinny is the offspring of a male horse and a
female donkey. There is a distinction, a material distinction to have
the cross breed known either as a mule or a hinny.
 
So is a mule/hinny a horse or a donkey? Using normal human convention,
the offspring is normally referred to as of the same breed or