Host, hospitality, hospital, hospice, hostel, hotel, hostile, hostility, ostler, and guest.
The words in the subtitle of this essay are all related in both form and meaning, though the relationships may not be immediately obvious. It may not be obvious that “hotel” and “guest” are related in form, or that “hospitality” and “hostility” are related in meaning, but as we trace the histories of these words, we can see the relationships.
All the words in the title of this group come from the same Proto-Indo-European root, “*ghosti”, but they have gone their different ways. (The asterisk means that this root is a reconstruction—as all Proto-Indo-European roots are reconstructions, since we have no written records from that early period.) The meaning of this root (according to Calvert Watkins’ American Heritage Dictionary of Indo-European Roots) was “stranger”, “guest”, “or “host”, or “someone with whom one has reciprocal duties of hospitality”.
Such reciprocal relationships of hospitality were an important feature of early Indo-European societies. If I come to visit your town, you have a duty of hospitality to me—I am your guest and you are my host—and if you come to visit my town, I have a duty of hospitality to you—you are my guest and I am your host. Such relationships are common throughout the Homeric epics. In Book Six of the Iliad, for instance, the Greek soldier Diomedes and the Trojan soldier Glaukos encounter each other on the battlefield; after some discussion they discover that their fathers were guest-friends, so they agree to part without fighting each other. The Ancient Greek the word for “stranger” is “xenos” (ξένος, pronounced “ksenos”) and the host/guest relationship is “xenia” (ξενἰα, pronounced “ksenia”). According to some linguists (including the great nineteenth-century linguist Karl Brugmann), the root “*ghosti” in the zero-grade, “gh-s”, is the origin of the Greek ξένος, with “gh-s” becoming “ks”. A stranger could potentially be either a friend or an enemy. I’m not sure that Brugmann’s etymology is formally correct, but “xenos” and “xenia” clearly belong to the same semantic field as the words derived from “*ghosti”. We get the English word “xenophobia” (“fear of strangers”) from this double-edged Greek word. I considered adding “xenophobia” to the list in the subtitle, but not all linguists accept Brugmann’s derivation, so I left it out.
The Indo-European root “*ghosti” is the origin of the Latin word “hostis” (and the Latin derivatives “hostilis” and “hostiliter”). This orginally meant “a stranger” but it came to mean “an enemy”, particularly a public enemy (as opposed to a private enemy, who was “inimicus”, that is, not an “amicus”—compare English “inimical”.) The English words “hostile” and “hostility” are derived from Latin “hostis”. The English word “host” can mean “an armed company” or “a multitude of men”. This meaning, which goes back to the late thirteenth century, is probably derived from “hostis” in the sense of “public enemy”—an opposing army is a multitude of public enemies. “Host” can also mean just “a multitude of things”, metaphorically, an army of things, as in “we were beset by a host of troubles” or “she had a host of ideas about how to solve the problem”; this meaning dates from the early seventeenth century.
The Latin word “hospes” is derived from a compound root, “*ghosti-pot-”—the “pot” can be found in such words as “potent”, so the compound means something like “master of hospitality”. The Old French “hoste” is derived from Latin “hospes” (or rather from the accusative case “hospitem”), with the loss of “p” somewhere along the way, probably for the ease of pronunciation. Old French “hoste” became Modern French “hôte”, which means either “host” or “guest”. The accent over the “o” is an indication that the letter “s” has been lost from the word—compare French “étude” to Spanish “estudio”, “éponge” to “esponja”, “école” to “escuela”, and so on. Where the Spanish and French picked up the initial “e” is another story.
Latin “hospes” is the basis of the Latin words “hospitalis”, “hospitalitas”, and “hospitium”, which then developed into Old French “hospital”; this was originally a place of lodging or an an inn, then a lodging for those in need, and then a place where people in need could receive care, and eventually a place where people receive medical care. The Modern French for “hospital” is “hôpital”, again with the accent on the “o” representing the loss of “s”. Modern French “hôtel” is derived from the Old French “hostel”.
Modern English has borrowed various forms of this group, such as “hospitality” and “hospital” and “hospice”. English has borrowed both “hostel”, with the “s”, and “hotel”, without it. In French, the word “hôtel” originally meant a large private residence, a town mansion, then a building where travelers are accommodated. In Modern French, “hôtel de ville” means “city hall”. In English, an “ostler” was originally an innkeeper and then someone who tends horses at an inn. I don’t think the word is common now, but I have read it from time to time in older English novels.
The Proto-Indo-European root “*ghosti” thus leads through two Latin words, “hostis” and “hospes”, to two groups of French and English derivatives. The words in the “hostis” group express hostility, in various modes, while the words in the “hospes” group express hospitality, again in various ways, but they all go back to the ways we think about strangers, either positively or negatively.
Meanwhile, the same Proto-Indo-European root “*ghosti” was taken over by some languages in the Germanic family; but whereas in the Latin family, the initial “gh” was simplified to “h”, in the Germanic family, it was simplified to “g”. (There are other instances of Proto-Indo-European “gh” turning into “h” in Latin but “g” in Germanic. Thus the root “*ghehb” becomes “give” in English but “habere” in Latin; the root “ghans” becomes “Gans” in German (compare English “gander”), and in Latin “*hanser”, which then became “anser”.) Thus the root “*ghosti” leads to the modern German noun “Gast”, which means “guest”, and various derivatives of that, such as “Gasthaus” (‘hotel”) or “Gastspeil” (“away-game”). The equivalent English word is “guest”. According to the usual laws of sound-change, the “g” in German should show up in English as “y”, as German “Garn” (“thread”) is the equivalent of English “yarn” and the “Gart-” in German “Garten” is the equivalent of English “yard”, so the English equivalent to “Gast” should be “yeast”. According to the usual explanation the irregular English form “guest” is explained by the influence of forms in other Germanic languages, such as Old Norse “gestr”.
All these linkages are reasonably certain (except for the etymology of “xenos”) but there are a couple of less certain etymologies worth mentioning. The word “host” can mean the bread consecrated in the Christian ceremony known as the Eucharist; this derives from Latin “hostia”, the victim in a sacrifice, from the Latin verb “hostio”, which means “to strike”—the sacrificial victim was killed by striking it. Some etymologists speculate that this meaning is ultimately derived from the same Proto-Indo-European root “*ghosti”, but there is no general agreement. The word “hostage” derives from Old French “ostage”, which had a variety of meanings, including “rent, tribute, compensation” or “a guarantee, pledge, bail”, or “a person given as security”. The ultimate origin of this word is uncertain; some etymologists take it from Old French “hoste”, meaning “guest, and then “a lodger held by a landlord as security”, but others take it from Latin “obses”, derived from “ob” (meaning “before”) and “sedere” (“to sit”). When experets disagree, the amateur etymologist should probably not take a strong position, but I know where I would put my money.