transition metal
noun/trænˈzɪʃn metl/
/trænˈzɪʃn metl/
(also transition element)
(chemistry)- one of the group of metals in the centre of the periodic table (= a list of all the chemical elements) that form coloured compounds and often act as catalysts (= substances that make chemical reactions happen faster)
过渡金属（位于元素周期表中心的一组金属元素，可形成有色化合物，常作为催化剂）