eon
n. countable C1 Advanced US //ˈiɑn// UK //ˈiːɒn// eon
n. a very, very long period of time. It is often used to describe the age of the universe or the history of the Earth.
n. an extremely long period of time, typically used in geological or astronomical contexts to describe vast chronological spans.
It felt like an eon since I last saw my friends.
The geologist explained that the formation of the mountain range took place over several eons of tectonic pressure.
While human history is measured in millennia, the universe itself has existed for billions of years, spanning an eon of cosmic expansion and stellar evolution.
From Latin aeon, from Ancient Greek αἰών (aiṓn, “age, era”).