VCL A application framework library for Microsoft Windows and Borland Software Corp.'s Delphi and C++Builder rapid application development software. VCL was originally designed for Delphi but is now also used for C++Builder. This replaces OWL Object Windows Library as Borland's Windows C++ framework of choice. VCL encapsulates the C-based Win32 API into a much easier to use, object-oriented form. Like its direct rival, Microsoft Foundation Class Library (MFC), VCL includes classes to create Windows programs. The VCL component class can be inherited to create new VCL components, which are the building blocks of Delphi and C++Builder applications. VCL components are somewhat in competition with ActiveX controls, though a VCL wrapper can be created to make an ActiveX control seem like a VCL component.