ages
n. uncountablen. a very long time. You use this when you want to say you have been waiting or doing something for much longer than you expected.
n. an extended period of time. Used primarily in the plural form within informal or colloquial contexts to express hyperbole regarding duration.
I haven't seen my brother for ages.
We stood in line for ages before the ticket office finally opened.
The software update took ages to download, frustrating the developers who were already working against a tight deadline for the product launch.
Almost exclusively used in the plural form ('ages') to mean a long time; typically follows the preposition 'for' or 'in'.
I haven't seen him for an ageI haven't seen him for agesWhile 'an age' is grammatically possible, the plural 'ages' is the standard idiomatic expression for a long time in modern English.