§ Ered Myrn ’Black Mountains’ >> Eredvyrn (Mornvenniath) (TI:124)
These are earlier names of Ered Nimrais, the ’White Mountains’ or ’White-horn Mountains’ (see 3.14).
The first two forms consist out of N. ered, pl. of orod ’mountain’ (ÓROT-) and myrn, pl. of morn ’black’ (MOR-,VT45:35), lenited to vyrn in the second word.
Mornvenniath has been analyzed by Patrick Wynne in Lambengolmor message #799  as probably containing N. ment ’point’ (MET-), menn- medially and iâth ’fence’ as in Doriath ’Land of the Fence’ (WJ:370).