Green’s Dictionary of Slang

(N.Z. prison) an inmate who prefers to remain in their cell, thus in v. use.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 86/2: hermit n. 1 an inmate who shuns the company of his fellow inmates and keeps to his cell most of the time [...] hermit v. to shun the company of others and remain constantly in one’s cell: ‘You hardly ever see x in the wing,he’s always hermiting.