Mule & Donkey Terminology
 
The terminology used with donkeys and mules can be confusing so I've provided a brief summary of some of the terms you may hear:

Jack - a male donkey
Gelding - a neutered male donkey, horse, or mule
Jenny - a female donkey
Jennet - a female donkey
Mule - the result of crossing a donkey stallion with a horse mare.
Hinny - the result of crossing a horse stallion is crossed with a donkey mare
Molly - a female mule
John - a male mule, normally gelded
Mammoth Jackstock - the largest type of donkey reaching sizes as large as 16+ hands
Hand - measurement term used with all equines, each hand represents 4 inches, measured to the withers of the animal
Sire - father of an animal
Dam - mother of an animal

When a horse and donkey are bred, the resultant hybrid is normally sterile, although there have been a few documented cases of mule mares reproducing. Other than their lack of reproductive ability, mules can be used for any task for which a horse can be used. Mules retain the sure-footedness of their donkey ancestors, while possessing a more horse-like disposition. In appearance, mules draw a little from both sides. Mules will have the long ears of their donkey sire and a more upright mane and sparser tail than a horse. They usually inherit their body type from their dam's side. Although hinnies are the opposite cross (horse stallion to jennet), they do not differ significantly in appearance from a mule.