Gnosiology is "the philosophy of knowledge and cognition". In Italian, Soviet and post-Soviet philosophy, the word is often used as a synonym for epistemology. The term is also currently used in regard to Eastern Christianity.

Gnosis is the common Greek noun for knowledge. The term was used among various Hellenistic religions and philosophies in the Greco-Roman world. It is best known for its implication within Gnosticism, where it signifies a spiritual knowledge or insight into humanity's real nature as divine, leading to the deliverance of the divine spark within humanity from the constraints of earthly existence.