§ Elements in Quenya and Sindarin Names The Silmarillion

gwalh, wath 'shadow' in Deldúwath, Ephel Dúath; also in Gwathlo,the river Greyflood in Eriador. Related forms in Ered Wethrin, ThurIngwëthil. (This Sindarin word referred to dim light, not to the shadows of objects cast by light: these were called morchaint 'dark shapes'.)