Eon

Then about 2.3 to 2.5 billion years ago, during the Proterozoic Eon, blue-green algae called cyanobacteria, living in Earth’s shallow oceans, began emitting enough oxygen through photosynthesis to create the permanently oxygenated atmosphere that keeps us alive today.

Source: tatoeba (11119114)

It’s been eons since we last saw each other.

Source: wiktionary

Traditionally, a luncheon is a lunch that takes an eon.

Source: wiktionary

We live our lives in three dimensions for our threescore and ten allotted years. Yet every branch of contemporary science, from statistics to cosmology, alludes to processes that operate on scales outside of human experience: the millisecond and the nanometer, the eon and the light-year.

Source: wiktionary