groundsill means A timber beam used as the foundation for a building. Lexicurio rates it Sui generis — a strength score of 88 out of 100.
groundsill is pronounced /ˈɡɹaʊndsəl/.
Etymology
From Middle English groundselle, ground sille, equivalent to ground + sill.
noun
- A timber beam used as the foundation for a building.
- The lowest beam of a door-frame; the threshold.