undercroft
/ˈʌndərkrɔft/
noun
- A room or space beneath the ground floor of a building, especially a church or castle, often used as a crypt, storage area, or meeting place.
- Tourists explored the dark undercroft beneath the castle's great hall.
- The undercroft was converted into a small museum displaying ancient artifacts.
- The medieval church had a stone undercroft where monks once stored wine.