Koumpounophobia is the irrational fear of buttons. That's all you need to know about that; on to the etymology! The root appears to be koumpono, which is Greek for "button". As most Greek words do, koumpono traces to Ancient Greek, but people in Ancient Greece wore tunics and did not have buttons. Instead, the modern Greeks decided that their newfangled clothing item looked like a bean, so they borrowed the Ancient Greek word kuamos, which meant "bean". Further origins of this get hazier and hazier, so to avoid inaccuracy, let's just digress to the suffix -phobia, which is well known (Wikipedia lists 187; there are countless beyond that). This is from Greek phobos, which meant "fear" and was also the god of fear, from Proto-Hellenic phegwomai, from Proto-Indo-European bhegw, which meant "run", under the connection that you run from fear. So koumpounophobia, the fear of buttons, really is just running from beans.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.