The word ennui is surprisingly little-known. Meaning "a feeling of dissatisfaction or boredom", it comes from the Old French word enui, meaning "annoyance", since something that is annoying quickly becomes boring and dissatisfying. This is from the earlier root enoiier, meaning "bother", which in turn derives from Latin inodiare, or "to make loathsome". This is a combination of the modifier in- and the stem odiare, or "hate" (the connection is easy enough to see). This is from the earlier word meaning "hate", odio, from the root odi, which, as many Latin words do, traces to Proto-Italic, in this case the term odai, which is ultimately from the reconstructed Proto-Indo-European word which sounded something like od and also meant "hate". You can see that this word changed rather drastically towards gentrification; going from a strong, ancient feeling to a more modern, complex, and softer concept, showing how humanity changed along with the word.
Adam Aleksic, a leading contender for valedictorian of his high school, is a 208-month-old boy with disturbing interests in etymology, vexillology, geography, and law. Adam would like to one day visit Tajikistan and just won an essay contest on linguistics!
The Etymology Nerd