αιώνας

Etymology
From.

Noun

 * 1) century
 * 2) century
 * 3)  eon, era, age
 * 4) eternity, age, eon
 * 1)  eon, era, age
 * 2) eternity, age, eon
 * 1) eternity, age, eon
 * 1) eternity, age, eon

Usage notes
"Proterozoic eon" will be found translated as and. The form can mean any long period (age, century, etc) so  is often used to make the meaning clear.