Inside joke for the title. In Modern English, the word yellow has undergone a surprising amount of variation, encompassing forms such as yeller, yaller, yallow, yeallow, yullow, yelly, and yella, terms that were written down by people who dialectically used it that way or just couldn't spell. In Middle English, it got weirder still, with yelwe and yelou each making an appearance, and in Old English all the ys were replaced with gs to create words like geolwe, geolu, geolo, and geolue, all of which still carried the modern definition (such basic terms vary very little, since the meanings have always bern around). This is from the Proto-Germanic reconstructed root gelwaz, from Proto-Indo-European (or PIE) root gelhwos. After this we see our first variation and the last traceable word, PIE gelh, or "to shine", because of the sunny connection. Yellow meaning "cowardly" in Wild West slang came from a rascist slur for Chinese people, who were considered by xenophobic Americans to be sneaky and cowardly. And now you know.
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.