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 variables 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)