§ Nen-uinel (TI:364,361), Kerin-muil (TI:364)
These are earlier names of Nen Hithoel ’Mist-cool Water’ (UT:434), a lake formed by the river Anduin before Rauros.
The first form contains N. nen ’water’ (NEN-), but the second element is difficult to interpret. It may contain ui- ’eternal’ as in N. Uilos ’everlasting snow’ (OY-) or it may be related to UY- with Q. uile ’long trailing plant, especially seeweed’, [N.] uil ’seaweed’, but then giving #-nel a suitable explanation is difficult. The river Ruinnel ’Redway’ occurred earlier and I supposed that #-nel might be there the cognate of Q. nelle (< nen-le) ’brook’ (NEN-); perhaps it is used here with a changed meaning for a pool or lake?
But we may also analyze the name as uin-el and would then deal with the same ending as in Dant-ruin, Dant-ruinel above (2.39). In Goldogrin at least, uin was associated with water, with the archaic meaning ’wave’ and it was also the name of Ulmo’s whale (GL:74). A common word for ’whale’ was uimoth ’sheep of the waves’ with moth ’sheep’ (GL:58). However, in Early Noldorin uin (< *win-) means ’woman’ (PE13:155).
The second form seems to contain N. cerin ’circular enclosure’ (KOR-), later ’mound’ (UT:426), ’circular mound or artificial hill’ (TI:242-243) – but here perhaps just describing a place enclosed by a circular formation of hills. Muil also occurs in the name Emyn Muil, which is translated as ’Drear Hills’ in the index (UT:434), so that it would mean ’drear’. But originally it may have been intended to mean ’hidden’, from the stem MUY- with the adjective ending -l < -la as e.g. in S. fael ’fair-minded, just, generous’ (Q. faila, PHAYA-; PM:352). Although a note reads not in Noldorin because it became identical with moina, this root had earlier produced N. †muin ’secret’ (VT45:36). Hence, Kerin-muil might be *’hidden enclosure’. In the Fellowship of the Ring Nen Hithoel is fenced by steep grey hills (LotRII ch.9).
Another explanation would be G. muil ’tarn’ cognate to Q. moile (GL:58) already appearing in The Lost Tales contained in Umboth-muilin. Then kerin would be an adjective *’round, circular’ (cf. Ramas Coren below (3.28)) and hence Kerin-muil *’round tarn/lake’.