Judas window n. an aperture or glass pane that permits safe or surreptitious observation through a door or wall. Editorial Note: This is a variation on Judas hole, Judas trap, or just Judas. (source: Double-Tongued Dictionary)
Further reading
What’s up with ketchup? The shifting history and spelling of the name of this condiment. For centuries, ketchup was a fishy sauce originating in Asia—the tomatoes came only later! Plus, a new book shows what’s lost when a language dies: when there...
Sarah Jane in Tucson, Arizona, recalls hearing the phrase out where God lost his galoshes for any far-flung, hard-to-reach place. Similar phrases include where God left his overshoes, where Jesus lost his sandals, where Jesus lost his cap, where...