Architectural Design is a concept that focuses on the components or elements of a structure or system and unifies them into a coherent and functional whole, according to a particular approach in achieving the objectives under the given constraints or limitations. It is also the art and science of designing and superintending the erection of buildings and similar structures a style of building or structure buildings or structures collectively the structure or design of anything. For example, designing buildings, open areas, communities, and other artificial constructions and environments, usually with some regard to aesthetic effect. Architecture often includes design or selection of furnishings and decorations, supervision of construction work, and the examination, restoration, or remodeling of existing buildings.
Sources:
http://www.businessdictionary.com/definition/architectural-design.html
http://dictionary.reverso.net/english-definition/Architectural%20Design
http://dictionary.reference.com/browse/architecture