Green’s Dictionary of Slang

an adult person who indulges in entertainment, usu. film, videotape or television, geared to attract both child and adult audiences.

2001		Guardian 5 Apr. 🌐 If you can live fast, die young and leave a beautiful corpse, who’d be old and wrinkled and despised by society? Worse, who’d be erased from a youth-obsessed society like a vanished commissar? You have to stop being a kidult sometime.
2002		Observer 17 Mar. 🌐 Marketers devise new categories – kidults and middlescents – to describe the formalin generation.