Webster's English Dictionary

Enter the word to look up:

thorium

Cross references:
  1. element               
 
tho.ri.um \'tho-r-e--*m, 'tho.r-\ n [NL, fr. ON Tho-rr Thor] : a 
   radioactive tetravalent metallic element that occurs combined in miner als 
   and is usu. associated with rare earths