So, the day before yesterday I found out quite by chance when looking up something else* that according to the 12th century chronicler Gerald of Wales, the fairy's word for water was ydor and that for salt was halgein. He knew this because he'd talked to a man who in his youth had found the way into the land of the fairies. This young Elidyr had become friends with the fairies, until at his mother's urging he had stolen a golden ball, whereupon the fairies hid the entrance to their land so that he cd never find it again.
What interests me most about this story, other than the detail of two words in fairy-language,** is Gerald's investigative method. Rather than just rely on a rumor, he actually sought out Father Elidurus, who had been known as Elidyr in his youth, and got the story first-hand from him. So our researcher did his due diligence but it still produced what we may call a false positive.
current reading: between books
*the 'something else' being the current struggle between celtomania and celtoscepticism
**shades of Rhys's ond and fern
thought while wielding a kitchen knife
2 hours ago