A word for “dwelling, mansion, hall” derived from √MBAR “dwell” (PE17/64), most notably as an element in oromardi “lofty halls” in the Namárië “poem” (LotR/377). Its plural mardi indicates a stem form of mard-, but its uninflected form appeared as both short mar (PE17/64, 163-4; PE21/80) and longer marda (PE17/107; PE21/76). Tolkien described its meaning more precisely in some notes from the 1960s:
> The derivative form ✱mbardā became in Quenya marda: “a thing or place dwelt in, dwelling” and since it could be applied to the actual dwelling-places or buildings (alone or grouped) approached the sense “house”. Though it did not in fact refer to “buildings”, and could equally well be applied to dwelling-places of natural origin, such as caves or groves (PE17/107).
And in an earlier version of these notes:
> The usual word in Eldarin for a “home”, as the established residence of a family consisting of one or more associated buildings, was ✱mbā̆r (stem mbăr-), and ✱mbardā (an adjectival formation). In Q mar (stem mard-), a blending of the two, was used like “residence”, usually with a defining genitive, for the “great house” of a family (PE17/164).
In Tolkien’s later writings, it seems this word was distinct from and coexisted with Q. már (mar-) “home” (PE17/106, 164).
Conceptual Development: This word for “dwelling” was often intermingled and confused with már “home”, making its conceptual development difficult to trace. There are some other earlier words for which some extension was added to √MBAR. In the 1910s ᴱQ. marda meant “world” as in ᴱQ. Talka Marda “Smith of the World” (LT1/180; 15/8); in The Qenya Phonology Tolkien said marda had a dialectical variant ᴱQ. mára (PE12/24) and in the Gnomish Lexicon it had the form Marwa “World” (GL/18).
The Declension of Nouns from the early 1930s had an adverbial variant ᴹQ. marta “home” of ᴹQ. mar “house” (PE21/25, 27); this adverbial form became marda “home” in Common Eldarin: Noun Structure of the early 1950s (PE21/76). In the 1930s more generally the stem form of short ᴹQ. mar was frequently mard- (PE21/27; EtyAC/MBAR; LR/72) but not always (LR/63). The coexistence of már and mard- was not clearly established until the 1960s (see above).
Neo-Quenya: For purposes of Neo-Quenya, I would use marda primarily as a “dwelling” as in “a thing dwelled in”, usable of buildings but also of natural dwellings like caves. Of constructed dwellings, it generally applies to larger or more elaborate dwellings such as mansions and halls, as in oromar “high hall”. I would assume the same was true of natural dwellings, with marda only applicable to a complex of inhabitable caverns rather than an individual cave. For the home of an individual or family I would use már “home”, and for the building itself I would use cöa “house” (dwelling or not).
I would use mard- as the stem form of this word as with its plural mardi. Strictly speaking its uninflected form would be mar < ✶mbardā̆ after the ancient loss of short final *ă*, but in practice this was generally reformed to marda to make it more distinct from már “home”. Thus sissë i luinë marda (ná) “here is the blue mansion” but tassë i ninqui mardi (nár) “there are the white mansions”.
marda noun "dwelling" (PE17:107)