Kettle
A kettle is a device used for boiling water, mainly these days used for the making of hot drinks (tea or coffee), and some food items such as freeze-dried instant noodles, or powdered soup / sauce mixes.
In the old days before people had running hot water, they'd also be used to fill up the bath.
There a 2 main types of kettle - those powered by mains electricity, and those powered by an external heat source (such as the top of a gas cooker, or an open camp fire). It is also possible to obtain ones powered from a car's cigarette lighter socket, and a 3rd type known as a Kelly Kettle traditionally used by fishermen from the West of Ireland but becoming increasingly popular with other outdoorsy type people. That works by having it's own self-contained fire inside the metal casing which fits over the top of itself.
Alternative Uses of the word
A "Kettle" is also a term used by Railway enthusiasts when referring to a Steam Locomotive.