Āstika and nāstika
Āstika (Sanskrit: आस्तिक, IAST: āstika) and Nāstika (Sanskrit: नास्तिक, IAST: nāstika) are mutually exclusive terms that modern scholars use to classify the schools of Indian philosophy as well as some Hindu, Buddhist and Jain texts. The various definitions for āstika and nāstika philosophies have been disputed since ancient times, and there is no consensus.