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in architecture, any opening, usually oblique, cut through a wall or a pier in the chancel of a church to enable the congregation-in transepts or chapels, from which the altar would not otherwise be visible-to witness the elevation of the host (the eucharistic bread) during mass. Similar openings are sometimes furnished to enable an attendant to see the altar in order to ring a small bell at the appropriate intervals of the elevation of the Eucharist in preparation for communion or to permit someone in a vestry to notify the bell ringer. Hagioscopes are more common in England than in continental Europe.