Source : WordNet®

authentication
     n 1: a mark on an article of trade to indicate its origin and
          authenticity [syn: {hallmark}, {assay-mark}]
     2: validating the authenticity of something or someone [syn: {certification}]

Source : Free On-Line Dictionary of Computing

authentication
     
         The verification of the identity of a person or
        process.  In a communication system, authentication verifies
        that messages really come from their stated source, like the
        signature on a (paper) letter.
     
        (2001-03-16)