Judas window

Judas window (plural Judas windows)

1. A window enabling a prison guard to see into a cell without being seen by the prisoner.
   • 1989, James P. Sterba, Creighton Peden, Freedom, equality, and social change, page 314:

     A prisoner may be confined nude in a cell with a Judas window and intruded upon periodically while there. Strip searches are used arbitrarily, either in response to minor offenses or simply to intimidate.