Door to the crypts of Minas Tirith, so called “for it was kept ever shut save at times of funeral” (LotR/826). This is name is translated “Shut Door” or “Closed Door”, a combination of fen(n) “door” and hollen “closed” (PE17/98, RC/550). As an adjective, the second element should undergo soft mutation to chollen, and in his “Unfinished Index” of The Lord of the Rings, Tolkien admitted that the proper form of this name would be Fen Chollen (RC/550). Tolkien published the name as Fen Hollen, no doubt motivated by the desire to prevent mispronunciation of the name, the same reasoning his son Christopher Tolkien used for changing the name Narn i Chîn Húrin to Narn i Hîn Húrin in the published version of The Silmarillion.
Conceptual Development: In Lord of the Rings drafts from the 1940s, this name first appeared as N. Fenn Forn(en) “Closed Door”, with the variation N. Fenn Uiforn “Ever Closed [Door]” (WR/338, 341).
fen (“door”), [His.] hollen, sollen? (p.p. from hol- or sol- “close”)