There were a couple of words for “death” under the root ᴹ√WAN “depart” in The Etymologies of the 1930s: N. gwanath and gwanw, the latter from primitive ᴹ√wanwē (Ety/WAN). Tolkien specified that these words referred to the “act of dying”, as opposed to guru which was “Death as a state or abstract”. These death-words from ᴹ√WAN may originally have been euphemistic, or perhaps they refer to the departure of Elvish spirits to Valinor.

Neo-Sindarin: Most Neo-Sindarin writers adapted N. gwanw as ᴺS. gwanu to better fit Sindarin spelling conventions, as suggested in Hiswelókë’s Sindarin Dictionary (HSD). I would use the words gwanath and gwanu only for the death of individuals, and mainly for deaths that are natural or peaceful. For violent deaths I would use gurth instead, and for the state of death or Death as an abstraction I would use guru as noted above.