Definition & Meaning of "hot water bottle"

What is a "hot water bottle"?

A hot water bottle is a rubber or plastic container filled with hot water and closed with a stopper or cap. It is used to provide warmth and comfort by placing it against the body to relieve pain or keep warm in cold weather. Hot water bottles are commonly used for soothing muscle aches, cramps, or to ease discomfort from conditions like menstrual pains. They can also be used to warm beds or blankets.