The sword of Túrin translated “Iron of Death” (S/210), a compound of gurth “death” and ang “iron” (SA/anga, gurth).
Conceptual Development: In the earliest Lost Tales, this name appeared as G. Gurtholfin “Wand of Death” (LT2/83), where its final element was G. olf(in) “branch, wand, stick” (LT2A/Gurtholfin). In Silmarillion drafts from the 1930s, it developed into N. Gurtholf of the same meaning, where its final element was N. golf “branch” (LR/406, Ety/ÑGUR). It only adopted its final form and meaning in Silmarillion revisions from the 1950s-60s (WJ/83, 138).
The usual Sindarin word for “death”, derived from the root √ÑGUR of similar meaning (UT/39; Ety/ÑGUR).
Conceptual Development: This word dates all the way back to the Gnomish Lexicon of the 1910s (GL/43), anchored by well established names like Gurthang or Gurtholf(in), the name of Túrin’s sword. Tolkien experimented with various alternate forms over the years, such as G. urthu (GG/14), G. gurthu (GL/43), ᴱN. gurdh (PE13/146) and N. guruth (Ety/ÑGUR), but kept coming back to gurth as the basic form.
Neo-Sindarin: For purposes of Neo-Sindarin, I would use this word for death in general and especially violent death, as opposed to the more euphemistic [N.] gwanath or gwanu “death”, more literally “departure”.