Green’s Dictionary of Slang

(Aus./N.Z. prison) the ‘free world’ outside prison.

1953		I. Hamilton Till Human Voices Wake Us 18: There had been rumours for some time on the outer that the [detention] camps might be broken up.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Outer. 2. The real world outside of prison walls.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 132/1: outer, the n. the world beyond prison confines, mainstream society [...] outters, the n. = outer, the; outside.
2006		B. Matthews Intractable [ebook] The additional promise of a couple of grand once I got back to work on the outer sweetened the pot.