Source : Webster's Revised Unabridged Dictionary (1913)

Overload \O`ver*load"\, v. t. [imp. & p. p. {Overloaded}; p. pr.
   & vb. n. {Overloading}.] [Cf. {Overlade}.]
   To load or fill to excess; to load too heavily.

Source : Free On-Line Dictionary of Computing

overloading
     
         (Or "Operator overloading").  Use of a single
        symbol to represent operators with different argument types,
        e.g. "-", used either, as a {monadic} operator to negate an
        expression, or as a {dyadic} operator to return the difference
        between two expressions.  Another example is "+" used to add
        either integers or {floating-point} numbers.  Overloading is
        also known as ad-hoc {polymorphism}.
     
        User-defined operator overloading is provided by several
        modern programming languages, e.g. {C++}'s {class} system and
        the {functional programming} language {Haskell}'s {type
        class}es.
     
        (1995-04-30)