groundsill

== English == === Alternative forms === grunsel (obsolete) groundsel groundsell === Etymology === From Middle English groundselle, ground sille, equivalent to ground +‎ sill. === Pronunciation === IPA(key): /ˈɡɹaʊndsəl/ === Noun === groundsill (plural groundsills) (rare) A timber beam used as the foundation for a building. The lowest beam of a door-frame; the threshold.