Aging out is American popular culture vernacular used to describe anytime a youth leaves a formal system of care designed to provide services below a certain age level. There are a variety of applications of the phrase throughout the youth development field.
Age out is defined as someone young doing an event, class, activity, that's is meant for or done by older people than themselves
by Khobekoko January 10, 2017
1. The inescapable "tipping point" where people lose their sex appeal, status or eligibility because of advancing age.

2. The process now affecting most Baby Boomers in the United States.

3. Why the Rolling Stones won't be touring again soon.
They won't let David play in the band anymore. He's Aging Out!
by Peter Kobs July 31, 2009