The act and discipline of composing drawings that visually communicate how something functions or is constructed. The need for precise communication in the preparation of a functional document distinguishes technical drawing from the expressive drawing of the visual arts. Technical drawing is used for architecture and engineering. There are two methods of technical drawing: manual or by instrument and computer aided design. 

Source: Art & Architecture Thesaurus 

http://vocab.getty.edu/page/aat/300444366