of, denoting, or formed in the fifth period of the Palaeozoic era, between the Devonian and Permian periods, lasting for nearly 64 million years during which coal measures were formed
noun
2. the Carboniferous
carboniferous in American English
(ˌkɑrbəˈnɪfərəs)
adjective
1.
producing or containing carbon or coal
2. [usuallyC-]
designating or of the fifth geologic period of the Paleozoic Era, subdivided into the Pennsylvanian (the Upper Carboniferous) and the Mississippian (the Lower Carboniferous) and characterized by warm, moist climate and vast swamps which eventually formed into extensive coal deposits