I've read different definitions for what stewing is. I've read that it means to cook at a simmer(i.e. below a boil) but I've also read it means to cook in water in a pot with a lid.
If the latter that could still mean it is boiling since the water has been added to the pot of food, it s cooking on high heat and so still being boiled.
Technically speaking, its not clear to me what the difference between stewing and boiling is. I've read that stewing means less mineral loss so it helps to understand in that context also.