An earlier name for S. Deldúwath appearing in Silmarillion drafts from the 1930s, glossed “Deadly Nightshade” (LR/133) or “Night of Dread’s Shadow” (LR/406). It is a combination of gwath “shade”, fuin “night” and Daedhelos “Shadow of Fear”.
Sindarin
deldúwath
place name. Deadly Nightshade, (lit.) Horror of Night-shadow
Elements
Word Gloss del “horror” dû “night, dimness; dim, dark, night, dimness; [N.] night-fall, late evening; [S.] dim, dark” gwath “shadow, dim light, shadow, dim light, [N.] shade”
Another name for Taur-nu-Fuin, the forest of Dorthonion corrupted by Morgoth (S/155). Tolkien generally glossed this name as “Deadly Nightshade” (WJ/282, LR/282), but it is a combination of del “horror”, dû “night” and the lenited form of gwath “shadow” (SA/del, dú, gwath), hence literally meaning “Horror of Night-shadow” (SI/Deldúwath).
Conceptual Development: In the earliest Lost Tales, this forest was referred to only by its other name, G. Taurfuin “Forest of Night” (LT2/47). Starting in the Lays of Beleriand from the 1920s, Tolkien sometimes referred to the forest in English as “Deadly Nightshade” (LB/34). An Elvish form of this second name first appeared in Silmarillion drafts from the 1930s, initially as N. Math-Fuin-delos (SM/299), later changed to N. Gwathfuin-Daidelos (SM/311). In the mid-30s he changed the name again to N. Deldúwath (LR/147), a name that also appeared in The Etymologies as Deldú(w)ath (Ety/DEL). He used the form Deldúwath thereafter.