hahniumEnglishOxford Dictionary of Englishhahnium /ˈhɑːniəm / ▸ noun [mass noun] the name formerly proposed by the American Chemical Society for the chemical element of atomic number 105 (dubnium), and by IUPAC for element 108 (hassium). – ORIGIN 1970s: named in honour of Otto Hahn (see Hahn, Otto).