A coffer is a sturdy box or chest used to store valuable items, especially money, jewels, or important documents. In medieval castles, nobles kept their gold coins locked in heavy wooden coffers with iron bands and complex locks. Pirates in old adventure stories buried coffers filled with treasure on remote islands.

The word also appears in the phrase public coffers, which means the money belonging to a government or organization. When a town's coffers are full, it has plenty of money to repair roads, run schools, and pay for services. When the coffers run low, tough choices have to be made about spending.

You might also encounter coffers in architecture: the decorative sunken panels in fancy ceilings. The Pantheon in Rome has a magnificent domed ceiling covered in square coffers that reduce the weight of the massive structure while creating beautiful geometric patterns.

The key idea connecting these meanings is containment and value. Whether holding actual treasure, representing collective wealth, or creating architectural beauty, coffers suggest something worth protecting and preserving.