lightwell

plural lightwells

1. architectureAn open shaft that transmits light from above into a staircase or an inner room.

   The sliding glass door with its rolled-up blinds looked onto a lightwell, composed of a glass platform overhead and carefully angled mirrors that were reflecting a confusing cold light into the bedroom.

   2017, Kamila Shamsie, Home Fire, Bloomsbury (2018), page 240

   1 more example

   In it a covered porch and vestibule were backed by a vertical shaft or "light-well," which served as a great window both to the vestibule itself, and to the corridors, staircases, and landings that connected it with the upper stories.

   1907, Ronald M. Burrows, The Discoveries In Crete, page 80

   Synonyms: airshaft, air well, ventilation shaft, vent shaft