(Tomorrow is official Estonian Language Day)
When it comes to untranslatable expressions, the scale is often tipped toward Estonian, which has many words that don't have any one single counterpart in English.
Unlike the case of the legend about the number of Inuktitut words for snow, these aren't compound words I'm talking about.
For example, one that should be very salient this winter, with its lack of crisp, clear weather (and snow), is "karge". It's an odd one, often given as "harsh" but usually meaning "clean", "cold" and "spare", all at the same time. It's a little overused: if you hear the word "Nordic" ("Põhjamaa, põhjamaine"), about half the time you will soon hear the word "karge". And I would say it's often used as an excuse for why someone skimped on decorations -- as in, this white functionalist villa isn't a boring box, it's karge (representing a deep-seated quality of reticence that comes from our Nordic identity).
Speaking of architecture, another useful untranslatable word is "kammerlik", often used for such things as small but elegant Old Town apartments. It translates as a "tight little package", "refined" and "intimate" all at the same time -- kind of like the visual equivalent of chamber music.
Someone was just making the case that the word for nature, "loodus", is another untranslatable. Because if you say "Estonia has a very beautiful nature", you sound a little like Borat, right?
Actually this one is more of a missing concept in Estonian -- there aren't good words for "wilderness" and "great outdoors", so "nature" does double duty.
As in England and most of Europe, "wilderness" isn't really something you find in Estonia. The only true wildernesses in Estonia are, apart from some rocky islets, wetlands, and there you would just say the local word for bog or mire.
Environmentalism in Estonia has flirted with preservationism in some eras, but many typical countryside landscapes (as well as the most biologically diverse ones) are tall-grass meadows that are also shaped by humans and grazing, like, I suppose, the balds in the southern Appalachians of the US. The name for these is yet another untranslatable: pärandmaastik, heritage landscape.