DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   Na
       n 1: a silvery soft waxy metallic element of the alkali metal
            group; occurs abundantly in natural compounds (especially
            in salt water); burns with a yellow flame and reacts
            violently in water; occurs in sea water and in the mineral
            halite (rock salt) [syn: sodium, Na, atomic number
    11]