Definition from Wiktionary, the free dictionary
- (chiefly obsolete) Having the same.
- The two main players were roughly of an age.
1825 March 16, Robert Southey, “Letter XVII”, in Life and Correspondence of Robert Southey, pages 56:
- He and F were of an age and standing, the giants of the house, but F was the braver, and did us the good office of keeping him in order.
1854, Elias Darnell, Journal of the Campaign, pages 74:
- Allen said, "If we were of an age, and on an equal footing, you would not give me the lie so often."
- (idiomatic, dialectal) Indicates a more or less habitual activity during the given part of the day.
- Of an evening, I like to play chess. i.e., On some evenings, I like to play chess.
- Of a morning, they would work in their garden. i.e., They generally worked in their garden in the morning.
The first sense functions as an adjective and is generally used with be. The second sense functions as an adverb.
The phrase of a can also occur naturally in a prepositional phrase using of (e.g., the shell of an egg).