Green’s Dictionary of Slang

Aro n.

(N.Z. prison) Arohata Women’s Prison, Wellington.

[NZ]D. Looser ‘Boob Jargon’ in NZEJ 13 27: aro or arrow n. Arohata Women's Prison, Wellington.
[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 7/2: Aro (also Arrow) n. Arohata Women's Prison, Wellington.