Board Thread:The Panopticon/@comment-25117610-20161123164500/@comment-24894325-20161220191829

Yes, it's called Past Participle and used as an adjective.

"Participle: a word having the characteristics of both verb and adjective; especially : an English verbal form that has the function of an adjective and at the same time shows such verbal features as tense and voice and capacity to take an object"