- (initialism|lang=en) . (politics) ΕΟΝ, the Greek '''National Organisation of Youth''' similar to the Hitler Youth, it was formed before WWII and disbanded in 1941.
- Noun. (US) Eternity.
- Noun. A period of 1,000,000,000 years.
- Noun. (geology) The longest time period used in geology.
- Noun. (US, informal) A long period of time.
- Noun. (Gnosticism, usually spelled aeon or æon) A spirit being emanating from the Godhead.