lond (“entrance to harbour, land-locked haven”), daer (“great”) #Dh could revert to d, assimilated by the preceding d.
Sindarin
lond daer
place name. Great Haven
Lond Daer
noun. great haven
lond daer enedh
place name. Great Middle Haven
Númenorean harbor at the mouth of the river Gwathló, translated “Great Haven” (UT/263), a combination of lond “haven” and daer “great”.