The term 'vessel for boiling water' can be summarized by two crossword solutions: 'POT' (3 letters) and 'KETTLE' (6 letters). A POT is a deep, round container with a handle and a lid, usually made of metal or ceramic, used for cooking food. A KETTLE is a metal container with a lid and a spout, used for boiling water. Both pots and kettles are commonly used in kitchens to heat water for tea, coffee, or other beverages.