An engineer is a person who uses scientific knowledge to design, construct, and maintain engines and machines or structures such as roads, railways, and bridges.

An engineer is a person who repairs mechanical or electrical devices.

An engineer is a person who is responsible for maintaining the engine of a ship while it is at sea.

When a vehicle, bridge, or building is engineered, it is planned and constructed using scientific methods.

If you engineer an event or situation, you arrange for it to happen, in a clever or indirect way.