or Judas Holes. The peep-holes in a prison-door, through which the guard looks into the cell to see if all is right; when not in use, the holes are covered up.
“It was the faint click made by the cover of the `Judas' as it falls back into the place over the slit where the eyes have been.” —The Century: Russian Political Prisons, February, 1888, p. 524.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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