1. An epoch in the Pennsylvanian, dated at 306.5–303.9 Ma ago (Int. Commission on Stratigraphy, 2004) comprising the Krevyakinskian, Chamovnicheskian, and Dorogomilovskian ages (these are also stage names in eastern European stratigraphy). The Kasimovian is preceded by the Moscovian and followed by the Gzhelian epochs.

2. The name of the corresponding eastern European series, which is roughly contemporaneous with part of the Stephanian (western Europe), and the Missourian and lower Virgilian (N. America).