When I was studying Physics, we called it science. When I was studying Engineering, we called it engineering. When I was, briefly, a high school teacher, we called it science and math. I worked as an engineer for at least 20 years before I ever heard of ‘stem’ as other than a botanical or glassware term ...
The term STEM was invented a couple of years ago by the Obama administration. They are trying to get the “disadvantage” into the tech world.