DuckCorp Dico

Found one definition

1.                 From WordNet (r) 3.0 (2006):
                   
   
   
                   
                     
   u
       adj 1: (chiefly British) of or appropriate to the upper classes
              especially in language use
       n 1: a base containing nitrogen that is found in RNA (but not in
            DNA) and derived from pyrimidine; pairs with adenine [syn:
            uracil, U]
       2: a heavy toxic silvery-white radioactive metallic element;
          occurs in many isotopes; used for nuclear fuels and nuclear
          weapons [syn: uranium, U, atomic number 92]
       3: the 21st letter of the Roman alphabet [syn: U, u]