Medium
Medium began life as me, a preposition meaning “between” in Proto-Indo European. A suffix dhyo was sometimes added to make this preposition into medhyo, an adjective meaning something analogous to “betweenish” or “middle”, e.g. “the middle house” (the one between the other two).
In Latin, medhyo became medius. That is, medius was used with masculine singular nominative nouns — but it could also be medii (masculine singular genitive), mediae (feminine singular genitive), and medium (neuter singular nominative), among others. It was this last form, of course, that was picked up by English in the 1500’s (when everybody who was anybody knew Latin) and used either as an adjective (as in Latin and PIE) or as a noun meaning “middle ground” — that which appears between other things.
Once in English, it began to acquire other, related meanings. In the 1600’s it began to be used to mean a channel of communication, and in 1853 it first appeared meaning a “person who conveys psychic messages”, from the idea that the psychic is acting as a channel of communication with the Spirit world.
Phonosemantically, the word starts with a manifestation / creation (”m”) which is carried forward over some distance (long “e”) to a decision or doorway “d”. Afterwards it may be carried further (long “e”) and released into thought (short “u”) before passing to a second manifestation (”m”). It’s striking, I think, how these sequence of sounds conveys the idea of a message generated at the beginning of the word, carried over distance and crossing a boundary, and released into thought — only to generate another message in return!
It’s fascinating to compare this to media: the plural form of the original Latin medius, used today as the plural of medium (but, interestingly, not for psychic mediums!). Phonosemantically, it is identical to medium, except no return message is indicated! See how well this fits with modern usage: television and movies and radio, one-way transmissions, are the media; but the internet isn’t — it’s called a medium.
Thanks to Slade for suggesting this word of the day.





