It would seem weird to use the word mnesia in English, but when we attach a one-letter prefix meaning "not" in front of it, it's suddenly normal. That's exactly what's happening on an etymological level here: our word amnesia, which comes from Ancient Greek amnesia, is composed of that prefix, a-, and the root mnesia, meaning "to remember" (so, together, amnesia means "not remembering"). A-, through Proto-Hellenic, comes from Proto-Indo-European n (yes, just the letter), which meant "not". Mnesia, of course, isn't too complex, either; it can be conjugated to mnasthai ("recall"), which, also through Proto-Hellenic, comes from Proto-Indo-European. In this case, the reconstruction is men, meaning "to think". Usage of the word amnesia, which was first attested in 1786, has skyrocketed in recent years as its meaning becomes less medical and more used in popular culture. What was I talking about again?
Hello! I'm Adam Aleksic, a junior studying government and linguistics at Harvard University, where I co-founded the Harvard Undergraduate Linguistics Society. In addition to etymology, I also really enjoy trivia, politics, vexillology, geography, board games, conlanging, art history, and law.