Proto-Sino-Caucasian: *nHǟ́ƛ̣wV̆
Meaning: dark, blue
Comments and references : The semantic connection of 'blue' and 'iron' is found in PNC *nHǟƛ̣_wV̆ 'blue; (blue metal) > iron' and Bsq *urdi-n 'blue, gray', *burdina 'iron'. It is uncertain whether this association existed already in the ancestor of Bsq and NC, or developed independently. If original, the word may have referred to rare, and expensive, meteoric iron.