/hoʊst/
[noun] A person who welcomes and entertains guests, or a large number of people or things. The word can also refer to a living creature that supports a parasite, or the bread used in a Christian church ceremony.
'Host' secretly contains two opposite Latin words — one meaning 'guest' and one meaning 'enemy' — and both live inside it at the same time.
Few English words carry as many lives within them as 'host', and the reason lies in a remarkable accident of Latin history. The word traces back to two ancient Latin roots that were actually related to each other: 'hostis', meaning 'stranger' or 'enemy', and 'hospes', meaning 'guest' or 'host'. Both come from the same ancient Proto-Indo-European root, '*ghostis', which meant simply 'stranger'. In the ancient world, a stranger could be either a guest you welcomed or an enemy you feared — and Latin kept both possibilities alive in two separate words that eventually flowed into English along very different paths.
The 'enemy' branch gave English the word 'hostile' and, most dramatically, 'host' in the sense of a great army. This meaning arrived through Old French 'host' or 'ost', which itself came from the Latin 'hostis'. When medieval English writers spoke of 'a host of angels' or 'a host of soldiers', they were drawing on this military tradition — a host was a vast armed force, an overwhelming number. The sheer size of an army is why we still use 'a host' to mean a very large quantity of anything, as in 'a host of problems'.
The 'guest' branch is equally fascinating. Latin 'hospes' — meaning both the person who gives hospitality and the person who receives it — passed into Old French as 'hoste' and then into Middle English as 'host' by the 14th century. This is the host who greets you at a dinner party or manages a hotel. Remarkably, the very same Latin root 'hospes' gave us 'hospital' (a place of welcome for travellers and the sick), 'hotel' (from Old French 'hostel', from Latin 'hospitale'), 'hospice', and 'hospitality' — all through the chain Latin 'hospes' → Late Latin 'hospitalis' → Old French 'hostel' and 'hospital' → Middle English. So your hotel, your hospital, and your dinner party host are all, at their roots, the same ancient idea.
A third meaning — the Host as the sacred bread of the Christian Eucharist — comes from yet another Latin word: 'hostia', meaning a sacrificial offering or victim. This passed directly from Latin into Old French 'hoiste' and then into Middle English as 'host' by the 13th century. The connection to sacrifice gave the word its specific religious weight. Here, 'host' has nothing to do with strangers or armies — it is purely about offering. Yet by coincidence of sound, all three meanings collapsed into a single spelled word in English, creating one of the language's most quietly remarkable homonyms.
In modern English, we use 'host' almost without thinking — to host a party, to describe a TV show host, to refer to a biological host that carries a parasite, or even a computer server that hosts a website. Each of these uses carries a different ancient ancestor inside it. The party host descends from 'hospes'. The host of problems descends from 'hostis'. And the communion wafer descends from 'hostia'. One short, simple word — and beneath it, three entirely separate rivers of meaning flowing from the same ancient mountain: the unnamed, slightly frightening figure of the stranger at the door.