In Roman architecture, what do the terms "coffers" refer to?

Coffers are recessed geometric shapes in ceilings, often found in classical architecture, including Roman structures. These ornamental depressions are created to both reduce the weight of the ceiling and enhance its decorative appeal. The use of coffers can be seen in famous buildings such as the Pantheon in Rome, where they not only contribute to the aesthetic quality but also reflect the ingenuity of Roman engineering. By creating intricate patterns, coffers also help to break the monotony of flat surfaces and create visual depth, making them a significant feature in the overall design of vaulted or arched spaces in Roman architecture.