köken: From Middle Dutch nors, norts (“surly”), with further origin disputed. Possibly from nort (“north”) + -s (equivalent to modern noord + -s), due to the north being associated with negative character traits. If so, a doublet of noords. Or, less likely, from the sparsely attested verb norren (“to grumble”).
köken: Ultimately from Proto-Slavic *xmura, related to *xmuriti (“to make cloudy”). Compare Belarusian пахму́рны (paxmúrny) and пахму́ры (paxmúry), Polish pochmurny.
köken: From Old Danish thwær, from Old Norse þverr (“transverse, adverse, obstinate”), from Proto-Germanic *þwerhaz (“cross, adverse”), cognate with Swedish tvär, German quer, Dutch dwars, Gothic 𐌸𐍅𐌰𐌹𐍂𐌷𐍃 (þwairhs).