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1. of the state of Pennsylvania
2. (in North America) of, denoting, or formed in the upper of two divisions of the Carboniferous period (see also Mississippian (sense 2)), which lasted 30 million years, during which coal measures were formed
3. an inhabitant or native of the state of Pennsylvania
4. the. the Pennsylvanian period or rock system, equivalent to the Upper Carboniferous of Europe
A division of late Paleozoic geologic time, extending from 320 to 280 million years ago, varyingly considered to rank as an independent period or as an epoch of the Carboniferous period; named for outcrops of coal-bearing rock formations in Pennsylvania.