age vs month of Sundays

age and month of Sundays both are nouns.

Word	Noun	Adjective	Verb	Adverb
age	Yes	No	Yes	No
month of Sundays	Yes	No	No	No

As nouns, month of Sundays is a hyponym of age; that is, month of Sundays is a word with a more specific, narrower meaning than age:

Other hyponyms of age include aeon, eon, blue moon, year dot.

age (noun)	month of Sundays (noun)
how long something has existed	a time perceived as long
a time of life (usually defined in years) at which some particular qualification or power arises
a late time of life
an era of history having some distinctive feature
a prolonged period of time