Actinium

[æk'tɪnɪəm]

解释:

(noun.) a radioactive element of the actinide series; found in uranium ores.

编辑:威尔玛--From WordNet

解释:

(n.) A supposed metal, said by Phipson to be contained in commercial zinc; -- so called because certain of its compounds are darkened by exposure to light.

校对:卢埃林