The utilization of computer technology in architectural design has enormous potentials to enable the designer to put more time in thinking creative thoughts. The aim of this study is to enhance the potentials by developing language system which supports the designer to express his idea of architectural form. Fundamental requirements for the language system to denote architectural form are outlined through categolyzing the vocabularies collecting from architectural literatures and as results of experiments; a) denoting the form of FARNSWORTH HOUSE by language expression and b) remaking a plan and elevation of FARNSWORTH HOUSE only from the language expression. A basic model which is based on the above requirements is proposed as a language system denoting architectural form. This model is implemented as a part of CAD system and is tested its efficiency in utilization.