Business
Business is the activity of making one's living or making money by producing or buying and selling goods or services. Simply put, it is "any activity or enterprise entered into for profit. It does not mean it is a company, a corporation, partnership, or have any such formal organization, but it can range from a street peddler to General Motors." The term is also often used colloquially (but not by lawyers or public officials) to refer to a company, but this article will not deal with that sense of the word.
Engineering
Engineering is the creative application of science, mathematical methods, and empirical evidence to the innovation, design, construction, operation and maintenance of structures, machines, materials, devices, systems, processes, and organizations. The discipline of engineering encompasses a broad range of more specialized fields of engineering, each with a more specific emphasis on particular areas of applied mathematics, applied science, and types of application. See glossary of engineering.
Manager
The increase of this efficiency is essentially the problem of the manager, and the amount to which it can be increased by proper study is, in most cases, so great as to be almost incredible.
Henry Gantt (1910) Work, Wages, and Profits: Their Influence on the Cost of Living. p. 14