Answer:

eon

AnswerCrossword Clue
EONA billion years
EONA lo-o-ong time
EONAge
EONAges and ages
EONEternity
EONIndefinitely long time
EONLong, long time
EONA month of Sundays
EONMany eras
EONOne billion years in ONE?
EONRoughly forever
EONBig time
EONLong time
EONQuite a while
EONBasically forever
EONHundreds of generations
EONReally, really long time
EONSuper-freaking-long time
EONTime spent at the DMV, it often seems
EONLong long long long long long long time
EONMany ages
EONGeological time
EONUncountable years
EONVery long time
EONForever, seemingly
EONLong stretch
EONCountless years
EONYears and years
EONFrom here to eternity
EONGood long while
EONReally long time
EONTons of time
EONBig bunch of years
EONMany millennia
EONBig hunk of time
EONForever and a day
EONBig time division
EONImmeasurable time
EONBig stretch
EONMany a moon