Medieval historians are familiar with the many terms for horse types used in the middle ages, including destrier, charger, courser, palfrey, rouncey, hackney, and sumpter. These terms for differentiated types of horses seem to appear in literature before they appear in law. This may be misleading because of the scarcity of medieval sources, but it does suggest that the laws were passed to support the ideals illustrated by the literature. Increasingly fine distinctions, such as between rouncey, courser, and destrier, keep pace with the increasingly complicated social classes of the late middle ages. These terms also become conflated with the animals’ breeding rather than pure utility, such as the use of palfrey for a finely bred (often of eastern extraction) general riding animal as opposed to hackney for a common bred general riding animal. Most of these names come from Latin, and have been assumed to be holdovers from Rome. However, Rome had far fewer, and different, terms for their horses. As the horse in general becomes more symbolic of social station, each type becomes more strictly codified, and closely related terms, such as charger and destrier, are used less interchangeably.
These terms are distinctly lacking from any source prior to the 11th century, and do not appear to be common until much later. These terms- even those such as palfrey and destrier, which may have Latin cousins- appear to be late medieval inventions to reflect changes in breeding practices that went along with agricultural inventions and societal restructuring. The Oxford English Dictionary dates all of these terms to the early 14th century, a time that also saw a huge growth in literature, and changes in how horses were depicted in these texts. Le Dictionnaire Littré dates the French destrier, coursier, roussin, palefroi, and soummier to the late 12th or early 13th century. There is some disagreement among historians (when it comes up at all) as to what precisely each of these terms signifies. This is because their significance, both literal and literary, is not static. For example, a sumpter (soumpter) was first commonly a footman who handled packs, whether or not they were on an animal; but by the end of the middle ages it was any beast of burden. The meanings are, however, fairly consistent within a given time period across English, French (including Occitan), and Spanish (including Catalan). Several terms have cognates which appear to date to the 13th century in Middle German, Middle Dutch, and Italian. The fact that there are close cognates of ‘new’ words in such disparate languages suggest that they were part of European culture as a whole during these centuries, and makes it more unlikely that they are simply remnants of Latin language and ideology. Most of these words, unsurprisingly, are rooted in French, and their usage spreads alongside chivalric culture. This has supported the idea that the confluence of horses and rank stemmed from military usage; however, it is important to remember that chivalric culture bloomed in a time when pikeman, bowman, crossbowman, mounted infantry, and even the new cannon became vastly more important than the aristocratic knight. In addition, the symbolism surrounding medieval equines is not a linear hierarchy, nor does it apply strictly to military animals. By the end of the middle ages, a person’s precise role in the increasingly murky societal fabric could be determined by a few words describing their horse. The animal’s own class, or proto-breed, it’s sex, health, age, and even color reflected a nuanced interpretation of it’s owners estate, role, rank, and wealth.
 Both dictionaries list the first occurrences of these terms as being from literary sources, though both cite legal and other documents for other vocabulary. While it seems that English is very late in using these terms, it should be noted that French was still commonly spoken among the nobility of England.
 R.H.C. Davis, The Medieval Warhorse: Origin,Development, and Redevelopment (London: Thames and Hudson Ltd., 1989) is explicit about this, giving etymologies for a few words. As Davis’ work was for several decades the only modern work on the medieval horse, other historians have relied on it. The major problem with these etymologies is that he gives only that the word is “from the Latin.” They do not take in to account when or why terms changed drastically in meaning, such as Latin “para veredus” (literally “spare horse for riding,” a term for replacement mounts for messengers and soldiers) to the late medieval “palfrei”, a well-bred refined gaited horse generally suitable for aristocratic women. This is, I believe, due to Davis’ focus on the horse as a tool for war.
 Most late texts will specify ‘sumpter horse’ or ‘sumpter mule,’ but not always. Regardless, the term came to be used more commonly for the animal than the man.