topon. Deadly Nightshade, (lit.) Horror of Night-shadow
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 gwath¹ “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.