From Longman Dictionary of Contemporary Englishgrown man/womangrown man/womanan adult man or woman, used especially when you think someone is not behaving as an adult should Who ever heard of a grown man being scared of the dark? → grown
Examples from the Corpus
grown man/woman• Several that I saw were very old, bearded, emaciated and grim and deathlike, instead of babies, grown men.• And the old Porsche 911 which has the same effect, but for very different reasons, on grown men.• I was fourteen, but I guess I looked like a grown woman.• Nearly twenty years ago that was, and now you re a grown woman.• In this story about Shep, he is a grown man and the prosperous owner of a silk mill.• Not one grown man, aristocrat or peasant, is worthy of respect when you really know him.• Elsie had never seen a grown man cry before.• He' s a grown man - he should be able to cook for himself!• Grown men in three-piece suits were playing video games.• She's crazy -- a grown woman letting a girl order her around like that.• No wonder that many grown women rebel against them.• She was a grown woman, she was entitled to take a bit of comfort as and when she pleased. 