It follows that, if anyone claims that word X is untranslatable, all you need to do is translate that word's monolingual definition, which usually will be made of translatable words. This approach—usually called "free translation"—exists for all languages, but it's especially important when the two languages in question are very different. Another test: if translators regularly give up translating a word, opting for free translation or for words with a much distorted or diminished nuance, than that word is untranslatable.