The word aeon, also spelled eon or æon, means "age", "forever" or "for eternity". It is a Latin transliteration from the koine Greek word ὁ αἰών (aion), from the archaic αἰϝών (aiwon). In Homer it typically refers to life or lifespan, but by at least Hesiod it could refer to ages or generations. It has a similar meaning to the Sanskrit word kalpa and Hebrew word olam. A cognate Latin word aevum or aeuum (cf. αἰϝών) for "age" is present in words such as longevity and mediæval.
Although a proposal was made in 1957 to define an aeon to be a unit of time equal to one billion years (1 Ga), the idea was not approved as a unit of scientific measure and is seldom used for a specific period of time. Its more common usage is for any long, indefinite, period of time.
