Word Stories - March 14, 2023 - 2 min


Among people who love calculus almost as much as they love calories, March 14 is Pi Day and therefore a perfect time to enjoy a little pie. The math involved is deliciously simple: the value of pi (π) is roughly 3.14, and in modern calendars March 14 is the fourteenth day of the third month (3.14). By happy coincidence, pi sounds just like pie in English, so pie-eating is a centrepiece of the celebration. For people who also love words, this seems like a good enough opportunity to celebrate Proto-Indo-European (PIE) as well.

PIE is a theoretical reconstructed language that is thought to have died out about 5000 years ago. It’s commonly seen as the lost ancestor of a wide array of languages spoken around Europe and India, and thereby helps linguists explain why those languages often seem so strangely similar. The long-lost PIE root *reg- can be used, for example, to help understand why rex is “ruler” in Latin (as in Tyrannosaurus Rex), rix is “ruler” in Gaulish (as in Vercingetorix), rājan is “ruler” in Sanskrit (as in the British Raj), and so on. This month’s Word Stories instalment considers a few English words that highlight the impact and complexity of PIE’s linguistic legacy.


The roots of the word guest stretch back through the Old English gaest and the Germanic *gasti- to the Proto-Indo-European root *ghosti-, all of which also meant “guest”. The English word is thereby related to a range of terms for “guest” in the Indo-European language family, like Gast (German), gäst (Swedish) and gjæst (Danish). One surprising relative of the English word guest is the English word host. As it turns out, both are ultimately derived from the PIE *ghosti-, which might seem odd at first. One may wonder how a single ancient word could have been used to mean both “guest” and “host”, but there are indeed words out there called contronyms that can act as their own opposites. We can’t assume, either, that everybody thought just like us 5000 years ago. Given the formalized mutual obligations of ancient hospitality codes, *ghosti- probably just meant something like “anybody participating in a guest-host relationship.”


The word host first appears in English at the turn of the 13th century as a term for any person housing a guest, whether as an innkeeper (The South English Legendary, 1290) or out of courtesy (Handlyng Synne, 1303). The word was derived from the Old French hoste and thereby the Latin hospes/hospit- and ultimately the Proto-Indo-European *ghosti-, all of which could mean either “host” or “guest”. Anglophones experimented with using host to mean “guest” as well (as seen for example in J. Gower’s Confessio Amantis, 1390), but this kind of dual usage didn’t last in English. The word guest had taken root long before (also ultimately from the PIE *ghosti-), and it remained the English go-to word for “guest”.

In the same century, English began using the word host in its military sense of “(enemy) army”. This form of the word was borrowed from the Old French host/oost and thereby the Latin hostis (“enemy”), which also goes back in its own way to the PIE *ghosti- (since a guest or a stranger might be a foreigner therefore a threat). The adjective hostile was added a few centuries later, as the kind of attitude one might expect from an enemy army.


The same PIE root *ghosti- that indirectly gave English both host and guest is also the ultimate source of many words related to hospitality. The Latin word hospes (“guest/host”) gave rise to the Old French hoste (also meaning “guest/host”) along with a whole range of French words related to taking people in, and these words were themselves taken in by English over the centuries: hostel (14th century), hospital (14th), hospitality (14th), hospitable (16th), hotel (17th), hospice (19th), etc.

The p sound found in so many of these words related to hosting seems to have arrived via the Latin hospes from a proto-Italic form that sounded something like hostipotis. The ultimate root would therefore be the lost PIE root *ghostipotis, meaning something like “guestmaster” (*ghosti- or “guest” + *potis or “master”), referring to the kind of ancient patron figure who might be in a position to offer hospitality to many guests. The sheer number and variety of words derived from the Proto-Indo-European root *ghosti- (from guest to host and hospitable to hostile) provide a telling test case when it comes to fathoming the productivity and complexity of PIE’s linguistic legacy.

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