This is the 392nd most frequent Estonian word.
leedu
"Leedu" means "Lithuania" in English.
"Leedus" is the inessive case of "Leedu", used here to denote 'in Lithuania'.
Ma käisin suvel Leedus.
I visited Lithuania in the summer.
"Leedu" is used as a noun to denote Lithuania as a country.
Minu sõber on Leedu päritolu.
My friend is of Lithuanian origin.
"Leedu-keelne" is a compound word where "Leedu" specifies the origin or type (Lithuanian) of the textbook.