transition metal
noun [ C ] chemistry specialized uk/trænˈzɪʃ.ən ˌmet.əl/ us/trænˈzɪʃ.ən ˌmet̬.əl/ (also transition element)
过渡金属
any of a group of metal chemical elements including copper and gold that show more than one valency (= the number of hydrogen atoms that can combine with one of its atoms to form a compound)