Source : WordNet®

Nd
     n 1: a yellow trivalent metallic element of the rare earth group;
          occurs in monazite and bastnasite in association with
          cerium and lanthanum and praseodymium [syn: {neodymium},
           {atomic number 60}]
     2: a state of north central United States bordering on Canada
        [syn: {North Dakota}, {Peace Garden State}]

Source : Free On-Line Dictionary of Computing

ND
     
        {natural deduction}