ages, a long time, many years, many moons, an eternity, a very long time, eons, aeons(UK), an eon, an aeon(UK), an age, a long while, a good long while(informal), yonks(UK, slang)
Sense: Noun: age - very old or very young
Synonyms:
ageCollocations, old age, dotage, senility, infirmity, advanced age, advancing age, youthCollocations, young age, tender years, elderliness, mature years, juvenility