thallium (n.)youdaoicibaDictYouDict[thallium 词源字典]
rare metallic element, 1861, Modern Latin, from Greek thallos "young shoot, green branch" (see thallus) + element name ending -ium. So called by its discoverer, Sir William Crookes (1832-1919), from the green line in its spectrum by which he detected it. Related: Thallic.[thallium etymology, thallium origin, 英语词源]