I've worked here all of my 'adult life'. [=I've worked here since I became an adult]
People who are close friends as children aren't always friends as 'adults'.
The university offers a popular program of 'adult education'.
(..) he's the only father I have. Therefore, he is my model of manhood, and my estimation of him will govern the prospects of my adult relationships. So I hope you bear in mind that any knock at him is a knock at me, and I'm far too young to defend myself against such onslaughts. Mm-hmm. Go watch (..)1989 TvShow: The Simpsons Title: Simpsons Roasting on an Open Fire Season: 1 Episode 1