DIFFICULT TO EXIST

In recent days, there's been a lot of misinformation on the Internet about the etymology of the Japanese word for "thank you", arigato. Some claim that it comes from the Portuguese word obrigado, which also means "thanks". On the surface, it looks like it may be possible, since there are a ton of Portuguese words in Japanese due to contact with early traders (which I discussed yesterday). However, that etymology is too perfect to be true. It shifted over time from the word arigataku, which meant the same thing and was used more than a hundred years prior to the Portuguese arriving. The roots there are ari, which meant "to exist" and katashi, which meant "difficult". The combined definition of "difficult to exist" later shifted to "rare", which became "special", which became "nice to have", which became "thank you". That's a lot of semantic change, and even cooler than an Indo-European origin.