The term engineer properly denotes a person who has received professional training in pure and applied science, but is often loosely used to describe the operator of an engine, as in the terms locomotive engineer, marine engineer, or stationary engineer. In modern terminology these latter occupations are known as crafts or trades.
Between the professional engineer and the craftsperson or tradesperson, however, are those individuals known as subprofessionals or paraprofessionals, who apply scientific and
engineering skills to technical problems; typical of these are engineering aides, technicians,
inspectors, draftsmen, and the like.