The forest ruled by Galadriel, originally named in Nandorin Lórinand “Valley of Gold(en Light)” (UT/253) but adapted into Sindarin (LotR/1127) in imitation of Q. Lórien (UT/253), the realm of Irmo in Aman.
Possible Etymology: In English, it was often called the “Golden Wood” (LotR/337), so its initial element is likely a variant of the prefixal form glor- of glaur “gold” (without the “g” due to its Nandorin origin), while its final element could be the plural -ien “lands” of the suffix -ian(d), hence: “✱Golden Lands”.
Conceptual Development: In the Gnomish Lexicon from the 1910s, the Gnomish equivalent of ᴱQ. Lórien was G. Luriel >> Lûrien (GL/55) while in The Etymologies from the 1930s, its Noldorin equivalent was N. Lhuien (Ety/LOS). When the forest was first named in Lord of the Rings drafts from the 1940s it was Lórien (TI/234), which Tolkien indicated was a Lemberin name in drafts of the Lord of the Rings appendices (PM/36). The derivation given above was described in Tolkien’s later writings on the history of Galadriel (UT/253).