River in Beleriand (S/205) translated “Yellow River” by Christopher Tolkien (SI/Malduin), a combination of the root-form √MAL “yellow” and the lenited form of duin “river” (SA/mal, duin).
Sindarin
Malduin
noun. golden river
malduin
place name. Yellow River
Elements
Word Gloss MAL “gold, yellow, gold” duin “(large) river, (large) river; [N.] water”
mall ([Etym. SMAL-] malt “gold”) + duin (“long and large river”) David Salo: ”dh and mh were liable to revert to d and m when they came to follow a nasal after syncope” TolkLang message 19.31.