The phrase "water cooker" refers to a device or appliance that is used to heat water. It can also be called a kettle or a water heater. Its main purpose is to make hot water quickly and easily. Full definition
With just a little bit of experimenting, you'll know exactly how much water your cooker requires. (jenniferskitchen.com)
Temperature differential: The white of an egg dropped into boiling water cooks much faster than the yolk at the center, and that's trouble. (cookinglight.com)
The heat of carrots, and hot pasta water cooks it enough for us to eat. (chefdehome.com)