Mule-jennies are female mules, which are a hybrid of a male donkey and a female horse. There are several synonyms for this term, including molly, mare mule, and jenny. Mules have been used as work animals for centuries due to their strength and ability to carry heavy loads. They are also known for their intelligence and stubbornness, which can sometimes make them challenging to handle. Mule-jennies have been used in farming, transportation, and even in the military. These animals have played an essential role in human history and continue to be used in some parts of the world today.