The word fan, as in the thing that cools you down, has been in English for many centuries, dating back to Old English fann. Before then, in Latin, it was vannus. This could either be from Proto-Indo-European wet, meaning "to blow" or from Latin ventus, meaning "wind", which could be from the same PIE root. Now, there are a lot of puns made connecting the air-moving device to the definition meaning "admirer", but no etymological correlation. In actuality, fan is a clipping of fanatic, something that seems obvious now but most people have never thought about before. In Latin as fanaticus, this word had a more religious connotation, implying a zeal for God- and that's why it comes from the earlier word fanum, meaning "temple". Through Proto-Italic faznom, this hails from the Proto-Indo-European reconstruction dehs, meaning "God". Fanatic might also be a cognate of fancy. How fancy!
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