A mule is a cross between a horse and donkey. However, it's a cross between a mare (a female horse) and a jack (a male donkey, thus the name jackass).

The donkey and elephant are widely known as symbols of the Democratic and Republican parties in the US. President Andrew Jackson was nicknamed "jackass" and depicted as a mule by opponents — but ...

The donkey – a more polite and gender-neutral word for “jackass” – became the symbol of the Democratic Party. The word “jackass” remained a term of ridicule. Twain defends the jackass ...