nook-shaft
/ˈnʊkʃɑːft/ /ˈnʊkʃɑft/Architecture
noun
In Romanesque and Gothic architecture: a shaft set in the angle formed by the orders of a compound pier or arch or in the jambs of a doorway or window.
Origin
Mid 19th century; earliest use found in Robert Willis (1800–1875), engineer and architectural historian. From nook + shaft.