Etymon is the Ancient Greek for truly, or really, and it describes a word (or part of a word) that's given rise over time to another. For example the word musth, the state of excitement a male elephant experiences during the breeding season, has as its etymon the Persian word mast, meaning drunk.
photo by Geir Kiste
The idea is that if you look at the history of a word you will discover its true or real meaning. Unfortunately, as you can see with the musth example, it doesn't work.
What you will discover, though, is how people see (or have seen) the world.
And what could be more fascinating than that?
Word To Use Today: etymon is Greek. It first appeared in English in the 1570s, when it held the idea not only of truth, but being primitive, as well.