The term 'WHERE BILLS ARE KEPT' can be summarized as 'WALLET', which is a 6-letter word. A WALLET is a small, flat case that is used to carry personal items such as cash, credit cards, identification documents, and other small items. It is typically made of leather or fabric and is often secured with a zipper or snap closure. Wallets are commonly carried in pockets or purses and are an essential item for many people.