lightwells

Noun

lightwell (plural lightwells)

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