§ {Duil} Emyn Rain >> Emyn Rhain ’Border Hills’ (TI:268,287,314) < N. emyn, pl. of amon ’hill’ (AM2-) + N. rhein, rhain ’border’ (REG-)
This is the name for a hill range northwest of Mordor (see the map on page 314).
In the former example rhain looks to be lenited according to the rules of late Noldorin (e.g. Ennyn Ðurin Aran Vória ’The Doors of Durin Lord of Moria’ (TI:182)), in the latter it is not, as in subsequent Sindarin (e.g. Ennyn Durin Aran Moria (LotRII ch.4, Rgeo)).
The struck through Duil ’hills’ also occurs in Duil Rewinion (see 2.43).