The term 'TANK COVERING' can be solved by the word 'ARMOR', which is a five-letter word. ARMOR is a protective covering that is used to prevent damage from being inflicted to an object, individual, or vehicle. It is most commonly used in military applications, such as tanks, and is made of strong materials such as metal or ceramic. ARMOR is also used in other contexts, such as sports, where it is used to protect athletes from injury.