A male donkey is called a jack, a female is a jenny (sometimes spelled jennet), and a castrated male is a gelding. Those three terms form the backbone of donkey vocabulary, but the naming system goes well beyond sex. Young donkeys, hybrid offspring, and even the species itself carry different labels depending on context, region, and purpose. The terminology can feel like a puzzle, especially since some of the same words show up in horse circles with slightly different meanings.
Jacks, Jennies, and Geldings
The word “jack” refers specifically to an intact (uncastrated) adult male donkey. Jacks tend to be more territorial and assertive than their female counterparts, which is one reason the distinction matters beyond mere vocabulary. In breeding operations, jacks are the studs, and their management requires different handling strategies and housing than other donkeys.
A “jenny” is an adult female donkey. You will sometimes see the older spelling “jennet,” though that word historically also referred to a small Spanish horse, which can cause confusion in older texts. In veterinary and breeding literature, “jenny” is the standard modern term. Research on donkey reproduction consistently uses “jennies” when discussing gestation and foaling. One study of the Martina Franca breed, for instance, found that pregnancy in jennies lasts about 371 days on average, with the sex of the foal being the main factor that shifts that number, as male foals tend to extend gestation slightly.1PubMed. Factors affecting pregnancy length and phases of parturition in Martina Franca jennies A separate ultrasound-based study of jennies reported a similar average of roughly 371 days for full-term pregnancies.2PubMed. Field ultrasound evaluation of some gestational parameters in jennies
A “gelding” is a male donkey that has been castrated. The term is borrowed directly from the horse world, where it means exactly the same thing. Geldings are generally calmer and easier to manage than jacks, which is why castration is common in working and companion donkey populations. Veterinary research on donkey castration has examined both surgical and non-surgical methods, finding differences in pain responses, stress hormone levels, and inflammation between the two approaches.3Veterinary and Animal Science. Stress, lipid profile and inflammatory responses to flunixin meglumine administration in surgical and non-surgical castration in donkeys
Foals, Colts, and Fillies
A baby donkey of either sex is called a foal, just as with horses. A young male is a colt and a young female is a filly, again mirroring horse terminology. These age-based labels generally apply until the animal reaches maturity, usually around three to four years old, at which point a female becomes a jenny and a male becomes either a jack or a gelding.
Donkey reproduction has a few quirks that make foal-related terminology come up in conservation discussions. Donkeys have a relatively low foaling rate, a long interval between births, and a high neonatal mortality rate, all of which have contributed to declining donkey populations in some regions and breeds.4PubMed Central. An Overview of Donkey Neonatology The long gestation period of roughly a year means that a jenny typically produces one foal per year at most, and twins are extremely rare. For endangered breeds, every foal counts, which is why veterinary science pays close attention to neonatal care in donkeys.
Donkey, Ass, or Burro
These three words all refer to the same animal, but they carry different connotations and show up in different settings. “Ass” is the oldest English term and comes from the Latin asinus, which is also the species name: Equus asinus. Scientific papers still use Equus asinus as the standard taxonomic label.5PubMed Central. An anatomical and endoscopic study of the nasopharynx and larynx of the donkey (Equus asinus) The word “ass” fell out of casual use in English largely because of its unfortunate overlap with a common vulgarism, though it persists in formal and literary contexts. If you read older agricultural texts or the King James Bible, “ass” is the default word for the animal.
“Donkey” emerged in English sometime around the late 18th century. Its exact origin is debated. Some linguists have linked it to “dun” (referring to the grayish-brown color common to the animal) combined with the diminutive suffix “-key,” while others have connected it to the name Duncan. Whatever the etymology, “donkey” became the dominant everyday English word and remains so today in Britain, Australia, and much of the English-speaking world.
“Burro” is the Spanish word for donkey, and in the United States it is used primarily for the small feral donkeys found in the American Southwest. The Bureau of Land Management, for instance, manages populations of wild horses and burros on public land. In that context, “burro” has a specific legal and administrative meaning. Outside the American West, the word is less commonly used in English, though it appears in any region with strong Spanish-language influence.
Mules, Hinnies, and Other Hybrid Names
When donkeys breed with horses, the offspring get their own set of names, and which name applies depends entirely on which parent is the donkey. A mule is the offspring of a male donkey (a jack) and a female horse (a mare). A hinny is the reverse: the offspring of a female donkey (a jenny) and a male horse (a stallion). Both are hybrids between Equus asinus and Equus caballus.6PubMed Central. Comparing and Contrasting Knowledge on Mules and Hinnies as a Tool to Comprehend Their Behavior and Improve Their Welfare
Mules have been far more common throughout history. They were present in Mesopotamian art as early as the first millennium BCE and were essential working animals in Roman society.7ScienceDirect. Zonkey: A simple, accurate and sensitive pipeline to genetically identify equine F1-hybrids in archaeological assemblages The practical reason for this is straightforward: it is much easier to breed a jack to a mare than to get a stallion to mate with a jenny. Hinnies are produced less frequently and tend to be slightly smaller, since the jenny’s body size limits fetal growth.
Both mules and hinnies are almost always sterile because donkeys and horses have different chromosome counts (donkeys have 62, horses have 64, and the hybrid ends up with 63, which makes normal cell division during reproduction nearly impossible). Despite their sterility, mules in particular have been prized for centuries for their endurance, sure-footedness, and temperament that blends traits from both parent species.
There are even more exotic hybrid names. A “zeedonk” or “zonkey” is the offspring of a zebra and a donkey. These are rare and almost exclusively produced in captivity, but the terminology exists because zebras, donkeys, and horses are all members of the genus Equus and can sometimes interbreed. Archaeological researchers have developed genetic tools specifically to identify such hybrids in ancient remains, since skeletal differences between donkeys, horses, and their crosses can be subtle.
Size-Based Labels
Donkeys also get categorized by size, and these categories have their own informal naming conventions. A miniature donkey stands under about 36 inches at the shoulder. A standard donkey falls roughly between 36 and 54 inches. A mammoth donkey (sometimes called a mammoth jack when male) stands over 54 inches, with some individuals reaching 16 hands, which puts them solidly into horse-sized territory. The American Mammoth Jackstock breed was developed specifically for mule production: the larger the jack, the larger and stronger the resulting mule.
These size categories matter practically. Guidelines for using donkeys as livestock guardians, for example, specify that guard donkeys should be selected from medium to large stock and that extremely small or miniature donkeys should not be used, since they may not be able to deter predators effectively.8PubMed Central. A global review of Livestock Guardian Donkeys (LGDks) in the prevention of carnivore depredation
Why the Sex-Specific Terms Matter in Practice
Knowing the difference between a jack, a jenny, and a gelding is not just trivia. The distinction has real practical consequences for anyone keeping, buying, or working with donkeys.
Livestock guardian programs illustrate this well. Donkeys have a natural aggression toward canids, which makes them useful for protecting sheep and goats from coyotes and dogs. But the recommendations are specific about which donkeys to use: jennies and geldings make good guardians, while intact jacks should not be used as guard animals.8PubMed Central. A global review of Livestock Guardian Donkeys (LGDks) in the prevention of carnivore depredation Jacks can be aggressive toward the very livestock they are supposed to protect, and their territorial behavior can make them unpredictable. The same review noted that to increase the probability of bonding, donkeys should be raised from birth or placed at weaning with the sheep or goats they will guard.
In veterinary contexts, the terminology matters because jacks, jennies, and geldings have different health profiles. Research on pain behavior after castration in donkeys found that the animals displayed specific behavioral changes, including increased limb raising and decreased feeding, that could be tracked and treated with appropriate pain management.9PubMed Central. Post-operative pain behaviour associated with surgical castration in donkeys (Equus asinus) Understanding that a gelding has been through this procedure, and knowing what behavioral signs to watch for, is basic information for any donkey owner.
Where Donkeys Came From and How Names Traveled
The domestic donkey descends from wild African ancestors, though pinpointing exactly when and where domestication happened has been difficult. Genetic research points to an African origin, but donkeys are uncommon in the archaeological record compared to horses or cattle, and the markers for early domestication are harder to identify.10PubMed Central. Domestication of the donkey: timing, processes, and indicators The best current evidence suggests domestication took place in northeastern Africa roughly 5,000 years ago, likely from the African wild ass (Equus africanus).
As donkeys spread across continents, different languages developed their own names. Linguistic research has explored possible etymologies of ancient words for donkeys or donkey-like animals in Iranian and Chinese languages, tracing the linguistic trail alongside the physical movement of the animals along trade routes.11International Journal of Eurasian Linguistics. Following the Donkey’s Trail (Part I): a Linguistic and Archaeological Study on the Introduction of Domestic Donkeys to China The donkey arrived in China relatively late compared to its spread through the Middle East and Mediterranean, and the words used for it in Chinese reflect borrowing from Central Asian languages, suggesting the animals and their names traveled together.
In the Mediterranean and Middle East, the donkey accumulated layers of cultural and symbolic meaning alongside its practical roles. Donkeys carried Christ into Jerusalem, transported the Greek god Dionysus, and provided a mount for Muhammad, among many other appearances in religious and mythological traditions.12The Donkey in Human History. Why Donkeys? This symbolic prominence kept the animal visible in literature and art even as mechanization reduced its working role in wealthier nations.
The Bray and the Body
One of the most recognizable things about donkeys is their vocalization, the loud two-toned bray that sounds nothing like a horse’s whinny. The scientific name for it reflects its distinctiveness: researchers studying donkey anatomy found that the bray has both an inspiratory component (the “hee”) and an expiratory component (the “haw”), making it unusual among equids. The sound may be related to the shape of the donkey’s upper airway. Compared to a horse, the donkey’s nasopharynx is markedly narrower in its middle portion, and the laryngeal airway sits at a more acute angle relative to the nasopharynx.5PubMed Central. An anatomical and endoscopic study of the nasopharynx and larynx of the donkey (Equus asinus) Those structural differences essentially create different resonance chambers, producing a sound that carries much farther than a horse’s call. Jacks tend to bray more often and more loudly than jennies or geldings, particularly during breeding season, which is yet another practical reason the sex-based terminology matters to anyone living near these animals.
Terms People Confuse
A few common mix-ups are worth clearing up. People sometimes use “mule” as a generic term for any donkey, but a mule is specifically a hybrid with a horse mother and a donkey father. A donkey is a purebred Equus asinus, not a cross. Similarly, “jackass” is not a slang invention. It is simply the full form of “jack” (a male donkey that is an ass), and it was a perfectly standard agricultural term for centuries before it became an insult. The word’s slide into vulgarity has more to do with cultural attitudes toward donkeys, which have long been unfairly associated with stupidity and stubbornness, than with any inherent rudeness in the term itself.
Another source of confusion is whether “burro” means something different from “donkey.” It does not, at least not biologically. A burro is a donkey. The word just signals a specific regional and cultural context, typically the feral or semi-feral populations of the American West descended from animals brought by Spanish explorers. If someone offers you a “burro” and someone else offers you a “donkey,” you are being offered the same species.
Finally, people sometimes assume that donkeys are just small horses or that the two species are more or less interchangeable. They are not. Donkeys have different nutritional needs, different hoof structure, different pain expression, and different social behavior than horses. Veterinary texts increasingly emphasize that donkeys should not be treated as small horses, since misapplying horse-based protocols to donkeys can lead to under-treatment of pain and other welfare problems. The behavioral differences after castration, for instance, are subtle enough that handlers trained only on horses may miss signs of distress in donkeys.9PubMed Central. Post-operative pain behaviour associated with surgical castration in donkeys (Equus asinus)
Miniature Donkeys and the Pet Market
The rise of miniature donkeys as pets over the past few decades has brought donkey terminology into households that would never have encountered it otherwise. Miniature donkeys, sometimes marketed as “mini donkeys,” are a distinct size category rather than a separate breed in most registries, though the Miniature Mediterranean Donkey has its own breed standard in the United States. Pet owners quickly learn the jack-jenny-gelding vocabulary because breeders and veterinarians use it constantly, and because the behavioral differences between jacks and geldings become very apparent when the animal lives in your backyard rather than on a working farm.
Most miniature donkeys sold as pets are geldings, for the same reasons geldings are preferred as guardian animals: they are calmer, less territorial, and less likely to display the aggressive or amorous behaviors that make jacks challenging to keep in close quarters. Jennies are also popular as pets, though owners who keep a jenny and a jack together will eventually need to learn one more term: a foal.