Grown up and Of age

Of age and grown up are semantically related. in developed topic. In some cases you can use "Of age" instead an adjective phrase "Grown up", when it comes to topics like adult, fully grown, nubile.

Of age adjective - Having attained a specific age; (`aged' is pronounced as one syllable).

Grown up and of age are semantically related. You can use "Grown up" instead an adjective phrase "Of age".