Litost is a Czech word with no exact translation into any other language. It designates a feeling as infinite as an open accordion, a feeling that is the synthesis of many others: grief, sympathy, remorse, and an indefinable longing. The first syllable, which is long and stressed, sounds like the wail of an abandoned dog.
Under certain circumstances, however, it can have a very narrow meaning, a meaning as definite, precise, and sharp as a well-honed cutting edge. I have never found an equivalent in other languages for this sense of the word either, though I do not see how anyone can understand the human soul without it.