The word aeon , also spelled eon (in American English), originally meant "life", "vital force" or "being", "generation" or "a period of time", though it tended to be translated as "age" in the sense of "ages", "forever", "timeless" or "for eternity". It is a Latin transliteration from the koine Greek word ? ? (ho aion), from the archaic (aiwon). In Homer it typically refers to life or lifespan. Its latest meaning is more or less similar to the Sanskrit word kalpa and Hebrew word olam. A cognate Latin word aevum or aeuum (cf. ) for "age" is present in words such as longevity and mediaeval.
Although the term aeon may be used in reference to a period of a billion years (especially in geology, cosmology and astronomy), its more common usage is for any long, indefinite period. Aeon can also refer to the four aeons on the geologic time scale that make up the Earth's history, the Hadean, Archean, Proterozoic, and the current aeon, Phanerozoic.
In astronomy an aeon is defined as a billion years (109 years, abbreviated AE).
Christianity's idea of "eternal life" comes from the word for life, zoe, and a form of aeon, which could mean life in the next aeon, the Kingdom of God, or Heaven, just as much as immortality, as in .
According to the Christian doctrine of universal reconciliation, the Greek New Testament scriptures use the word "aeon" to mean a long period (perhaps 1000 years) and the word "aeonian" to mean "during a long period"; Thus there was a time before the aeons, and the aeonian period is finite. After each man's mortal life ends, he is judged worthy of aeonian life or aeonian punishment. That is, after the period of the aeons, all punishment will cease and death is overcome and then God becomes the all in each one . This contrasts with the conventional Christian belief in eternal life and eternal punishment.
The Order of Nine Angles, a UK-based Left Hand Path/Satanic organisation propose the concept of Aeons are central to the esoteric philosophy developed by the pseudonymous Anton Long, who wrote that "an aeon is the term used [by the O9A] to describe a stage or a type of evolution. Evolution itself is taken to result from a certain specific process - and this process can be described, or explained [or 're-presented' ] via a bifurcation of time. That is, evolution is an expression of how the cosmos changes over or through or because of,'time' - this 'time' having two components. These two components are the causal and the acausal ...
"An aeon is a manifestation, in the causal, of a particular type of acausal energy. This energy re-orders, or changes, the causal. These changes have certain limits - in both causal space and causal time. That is, they have a specific beginning and a specific end. A civilization (or rather, a higher or aeonic-civilization) is how this energy becomes ordered or manifests itself in the causal: how this energy is revealed. A civilization represents the practical changes which this energy causes in the causal -in terms of the effect such energy has on individuals and this planet. A civilization is tied to, is born from, a particular aeon. By the nature of this energy, a civilization is an evolution of life - a move toward a more complex, and thus more conscious existence ..."
Aeon may also be an archaic name for omnipotent beings, such as gods.
In many Gnostic systems, the various emanations of God, who is also known by such names as the One, the Monad, Aion teleos (? "The Broadest Aeon"), Bythos ("depth or profundity", Greek ), Proarkhe ("before the beginning", Greek ?), the Arkhe ("the beginning", Greek ?), "Sophia" (wisdom), Christos (the Anointed One) are called Aeons. In the different systems these emanations are differently named, classified, and described, but the emanation theory itself is common to all forms of Gnosticism.
In the Basilidian Gnosis they are called sonships ( huiotetes; sing.: huiotes); according to Marcus, they are numbers and sounds; in Valentinianism they form male/female pairs called "syzygies" (Greek , from ? syzygoi).
Similarly, in the Greek Magical Papyri, the term "Aion" is often used to denote the All, or the supreme aspect of God.