A variant form of Dor Firn-i-Guinar appearing in one of Tolkien’s letters from 1972 (Let/417). It differs from the common form in that it uses the plural gyrth of gorth for “The Dead” and that the verb inflection of cuina- “live” undergoes nasal mutation instead of soft mutation. The latter implies that the relative pronoun i is elided from a plural form in.
Conceptual Development: A similar variation N. Gyrth-i-Guinar appeared in Silmarillion drafts from the 1930s (LR/305).
Home of Beren and Lúthien after their return to life, translated “Land of the Dead that Live” (S/188). This name is a combination of dôr “land”, the plural firn of fern “dead”, the relative pronoun i “who” and the present plural inflection of the cuina- “live”, lenited to guinar by the preceding pronoun.
Conceptual Development: In the earliest Lost Tales, this name first appeared as G. (i·)Cuilwarthon “(The) Dead That Live Again” (LT2/41, 51). In the earliest Silmarillion drafts from the 1930s this form first persisted as Cuilwarthien (SM/133), but was soon revised to N. Gwerth-i-Cuina “(Land of) the Dead that Live” (SM/135). This name N. Dor Firn i Guinar first appeared in The Etymologies from the 1930s (Ety/KUY, PHIR). Nevertheless, the form Gwerth-i-guinar appeared in the initial Silmarillion revisions from the 1950s-60s (WJ/71) before Tolkien settled on its final form.
In both the 1930s and later, Tolkien occasionally used Gyrth as the word for “The Dead”, in N. Gyrth-i-Guinar (LR/305) and S. Dor Gyrth i Chuinar. See those entries for further discussion.