Gnosis is the common Greek noun for knowledge (, gnôsis, f.). The term is used in various Hellenistic religions and philosophies. It is best known from Gnosticism, where it signifies a knowledge or insight into man's real nature as Divine, leading to the deliverance of the Divine spark within man from the constraints of earthly existence.
Gnosis is a feminine Greek noun which means "knowledge". It is often used for personal knowledge compared with intellectual knowledge (εἶδειν eídein), as with the French connaitre compared with savoir, the Spanish conocer compared with saber, or the German kennen rather than wissen.
Latin dropped the initial g (which was preserved in Greek) so gno- becomes no- as in noscō meaning "I know", noscentia meaning "knowledge" and notus meaning "known". The g remains in the Latin co-gni-tio meaning "knowledge" and i-gno-tus and i-gna-rus meaning "unknown" and from which comes the word i-gno-rant, and a-gno-stic which means "not knowing" and once again this reflects the Sanskrit jna which means "to know", "to perceive" or "to understand".
A related term is the adjective gnostikos, "cognitive", a reasonably common adjective in Classical Greek.Plato uses the plural adjective γνωστικοί – gnostikoi and the singular feminine adjective γνωστικὴ ἐπιστήμη – gnostike episteme in his Politikos where Gnostike episteme was also used to indicate one's aptitude. The terms do not appear to indicate any mystic, esoteric or hidden meaning in the works of Plato, but instead expressed a sort of higher intelligence and ability analogous to talent.
Plato The Statesman 258e
In the Hellenistic era the term became associated with the mystery cults.
Gnosis is used throughout Greek philosophy as a technical term for experience knowledge (see gnosiology) in contrast to theoretical knowledge or epistemology. The term is also related to the study of knowledge retention or memory (see also cognition), in relation to ontic or ontological, which is how something actually is rather than how something is captured (abstraction) and stored (memory) in the mind.