Engineer (noun)

1. A person who designs, builds, or maintains engines, machines, or structures.
2. A person who devises plans or solutions.
3. A person who operates or is responsible for the operation of a train, ship, or other vehicle.
4. A person who applies scientific and mathematical principles to practical ends.
5. A person who uses their knowledge and skills for a specific purpose.

Origin:

Middle english enginer, from middle french engineer, from old french engin, machine, engine, from latin ingenium innate quality, talent, from in- + gignere to produce.

Examples:

1. He is an engineer for the company.
2. She is a civil engineer.
3. The engineer operated the train.
4. The engineer found a solution to the problem.
5. The engineer used his knowledge to design the bridge.