2 Geology relating to or denoting the later part of the Carboniferous period in North America, following the Mississippian and preceding the Permian, and corresponding to the Upper Carboniferous of Europe. This period lasted from about 323 to 290 million years ago.
1a native or inhabitant of Pennsylvania.
2 (the Pennsylvanian) Geology the Pennsylvanian period or the system of rocks deposited during it.
Pennsylvanian in other Oxford dictionaries
Definition of Pennsylvanian in the US English dictionary