Doriathrin
thall
adjective. steep, falling steeply (of river)
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An adjective meaning “steep, falling steeply (of river)” derived from primitive ᴹ✶stalrā (Ety/STAL). The [[ilk|initial [s] spirantalized the following [t] to [θ] (“th”)]], and the [[mp|[lr] became [ll]]], as suggested by Helge Fauskanger (AL-Ilkorin/thall).