ACTINIUM


Meaning of ACTINIUM in English

akˈtinēəm noun

( -s )

Etymology: New Latin, from actin- + -ium; from the darkening effect of light on some zinc sulfide

1. : a supposed chemical element once thought to occur in commercial zinc

2. : a radioactive trivalent metallic element resembling lanthanum in chemical properties formed by alpha radiation from protactinium and found especially in pitchblende — symbol Ac ; see actinide series , actinium series ; element table

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.