I. ˈrādēəm noun
( -s )
Etymology: New Latin, from Latin radius ray, beam + New Latin -ium — more at ray
: an intensely radioactive shining white metallic element of the alkaline-earth group that resembles barium chemically, that occurs in combination in minute quantities in pitchblende, carnotite, and other uranium minerals principally as the isotope of mass number 226 formed from uranium 238, having a half-life of 1620 years, and emitting alpha particles and gamma rays to form radon, and that is used chiefly in luminous materials (as paint made by admixture with zinc sulfide or other phosphor), in medicine especially in the treatment of cancer, and in radiography — symbol Ra ; see actinium series , element table, thorium series , uranium series
II. noun
( -s )
Etymology: from Radium, a trademark
: a smooth lustrous supple fabric made of silk or rayon in plain weave and used especially for women's clothing and curtains