Source : WordNet®

instantiation
     n : a representation of an idea in the form of an instance of
         it; "how many instantiations were found?"

Source : Free On-Line Dictionary of Computing

instantiation
     
         Producing a more defined version of some object
        by replacing variables with values (or other variables).
     
        1. In {object-oriented programming}, producing a particular
        {object} from its {class template}.  This involves allocation
        of a structure with the types specified by the template, and
        initialisation of {instance variable}s with either default
        values or those provided by the class's {constructor}
        function.
     
        2. In {unification}, (as used in {logic programming}, {type
        checking} and {type inference}), binding a {logic variable}
        ({type variable}) to some value (type).
     
        (1995-03-28)