the intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment
the making, modification, usage, and knowledge of tools, machines, techniques, crafts, systems, and methods of organization, in order to solve a problem, improve a pre-existing solution to a problem, achieve a goal, handle an applied input/output relation or perform a specific function
the branch of science and technology concerned with the design, building, and use of engines, machines, and structures.
the abstract science of number, quantity, and space. Mathematics may be studied in its own right (pure mathematics), or as it is applied to other disciplines such as physics and engineering (applied mathematics).