1. Of, relating to, or being the geologic division of the Paleozoic Era from about 359 to 299 million years ago. The Carboniferous Period follows the Devonian Period and precedes the Permian Period and includes the Mississippian and Pennsylvanian Periods. It is characterized, especially in the Pennsylvanian, by swamp formation and deposition of plant remains that later hardened into coal.

2. carboniferous Producing or containing carbon or coal.