Actinium
- 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.
The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.