Grok. Tharn.
Grok and tharn are my favorite made up words.
Grok is a Martian word that comes from the book by Robert A Heinlein, Stranger in a Strange Land. The translation of “grok” means to understand something on a deep, intuitive level, maybe even on a visceral level.
My other favorite word is “Tharn.” It comes from the 1972 book Watership Down by Richard Adams. In the book, when a rabbit stands perfectly still it is hoping to not be seen. There are rabbits in my neighborhood, and I have often seen then freeze up as I approach, as if by being ever so still I, and my dog, will not see them.
Tharn shows up in Middle English texts 1300-1500 but then falls into disuse. (Oxford English Dictionary)