leper's squint

low-side window, leper’s squint, offertory window, squint

A small low window, usually on the right side of the chancel, through which the altar may be seen.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.
References in periodicals archive ?
See if you can find "The Leper's Squint", through which the Lepers, who lived in the Valley below, would make their confessions to the parish priest whilst he and the congregation sat safely inside the building.
The church itself is of sandstone, mainly dating from 1860 but on the site of its medieval predecessor, still mentioned for its surviving leper's squint in a 14th century north wall.
Hence the ancient name for such an opening, "the leper's squint." Such is the vantage point available to progressive folk in this country in the present era.