Quite simply, use of a typecast (or some other method) to tell a compiler to disregard the ConstQualifier, and allow an object declared const to be mutated.
CeePlusPlus even has a special purpose operator for this; const_cast
CastingAwayConst has two legitimate uses: Dealing with a legacy interface which is ConstIncorrect, or implementing LogicalConstness if other means of doing so (such as mutable) are not provided.