Someone who takes the view that if its broken it should be fixed, if its not broken it needs to be taken apart to find out why, theoretically to make future designs not be broken, really to break it so they can fix it.
In general have advanced math and science skills, engineers solve practical problems and design things, not to be confused with scientists, who discover things, or workmen who make things.
The scientist discovers a new material and its properties, the engineer uses this to design a new building, the workman makes the building.
Often engineers have trouble socializing, this is because they speak and think in numbers, and have tendency to "mental multi-task" i.e. Halfway through a conversation they will devote half their brain to designing a better sort of person to talk to.
Whatever it says, if it doesn't have a degree, its not an engineer, its something that wants to feel important.