Wiktionary
vb. 1 (context idiomatic English) To reach a specific age where one is legally considered to be an adult. 2 (context idiomatic English) To mature, or become fully developed.
WordNet
v. reach a certain age that marks a transition to maturity
Wikipedia
Come of Age (also alternatively titled The Vaccines Come of Age) is the second studio album by English indie rock band The Vaccines, which was released on 3 September 2012. It follows their debut album What Did You Expect from The Vaccines?, released the previous year. It was produced by Ethan Johns and reached number one in the UK.
Usage examples of "come of age".
That child has now come of age, an event that has triggered a renewed burgeoning of the Faitha second Embrasure has occurred, under the command of the First Child, Anaster.
Warwick, however, in his devious way, had no intention of setting up a Catholic administration because he was in no doubt that the King, who would come of age in a few short years' time, had by now firmly and passionately embraced Protestantism.
That little boy I took to mosque school only a few weeks ago will have come of age as a young gentleman, without my guidance!
Teach Berengaria what she needs to know so that she can support her sister when they have come of age and into the inheritance that Henry and I mean to leave them.
It was easy enough to tell him, on a given day, that he had come of age, though actually two days were still to run.
The deeds can be transferred to your father's name until you come of age.