Long timespans (4)
I believe the answer is:
eons
(Other definitions for eons that I've seen before include "Vast ages" , "Years and years" , "Endless periods" , "Long periods of time - noes have it" , "Divisions of archaeological time" .)
I believe the answer is:
eons
(Other definitions for eons that I've seen before include "Vast ages" , "Years and years" , "Endless periods" , "Long periods of time - noes have it" , "Divisions of archaeological time" .)