eon
UK: ˈiːɒn | US: ˈiːɑːn
n. an indefinite and very long period of time; an age
n. (Geology) a unit of time equal to a billion years
n. (Philosophy) a cosmic cycle or vast era
The word "eon" traces back to the Greek aiōn (αἰών), meaning "age," "lifetime," or "eternity." In ancient Greek philosophy and cosmology, aiōn referred to cyclical time or the eternal cosmic order. Latin borrowed it as aeon, which entered Middle English via Old French. The modern spelling "eon" reflects its Greek root while simplifying the Latinized form. The geological sense (a billion years) emerged in the 19th century, aligning with scientific measurements of deep time.
The formation of these mountains took an eon.
In geology, an eon is the largest division of time.
The myth describes gods who ruled for countless eons.
His research spanned what felt like an eon.
Philosophers debate whether the universe operates in finite epochs or infinite eons.