DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   Rb
       n 1: a soft silvery metallic element of the alkali metal group;
            burns in air and reacts violently in water; occurs in
            carnallite and lepidolite and pollucite [syn: rubidium,
            Rb, atomic number 37]