This was a requested word. The word toilet actually has really unexpected origins. I'll start from the back: in Proto-Indo-European, there was the word teks, which meant "cloth". This eventually became the Latin word texo, which was affixed to the suffix -ela (which forms abstract nouns) to make tela. This hung around the Italic and later Romance languages until it was altered in Old French to the form teile, which was altered into toile. It still meant "cloth" at the time. As this became toilette in Middle French, the word took on the meaning of "clothes", not much of a semantic shift at all, even as it finally became toilet in English. But as the word developed in English, it took on more of a "putting on clothes" meaning, then a "dressing room" meaning, since you put on clothes in a dressing room. Many aristocratic dressing rooms had early plumbing fixtures, and thus the word became applied to those plumbing fixtures; the earlier uses were altogether dropped.
Adam Aleksic, a freshman studying linguistics at Harvard University, has been described as the internet's sixth most famous etymologist. He has disturbing interests in words, vexillology, geography, board games, limericks, and law, and he loves writing about himself in the third person.
The Etymology Nerd