Answer:

EONS

Answer	Crossword Clue
EONS	Millions of years
EONS	Forever
EONS	Forever, seemingly

EONS	Geologic times
EONS	Time periods
EONS	Ages
EONS	Long periods of time
EONS	Roughly forever
EONS	Years and years and years and ...
EONS	Wait at the DMV, it seems
EONS	Thousands of years

EONS	Many millennia
EONS	Really long time
EONS	Long, long time
EONS	Slow-to-pass spells
EONS	Gobs of time
EONS	Geological spans
EONS	Interminable times
EONS	A really long time

EONS	Billions of years
EONS	Long stretches
EONS	Seemingly forever
EONS	Long time to wait
EONS	Quite some time
EONS	Long periods
EONS	Ages and ages
EONS	Long, long time periods

EONS	Geological periods
EONS	Years and years
EONS	Geologic time divisions
EONS	Paleontological spans
EONS	Hyperbolic stretches of time
EONS	From here to eternity
EONS	Looooong times
EONS	Very long periods

EONS	Long times
EONS	Many millenia
EONS	A dog's age
EONS	Extensive periods
EONS	A looooong time