Mardil masc. name, "(one) devoted to the house", sc. the "house" of the kings (Appendix A; interpreted in Letters:386). This indicates that the first element can mean "house" in the sense of family or household (see mar, már). This Mardil is described as a good steward, possibly suggesting that mardil ("one devoted to the house/family") could itself function as a common noun "(faithful) steward".
Quenya
mardil
masculine name. Devoted to the House
Mardil
(one) devoted to the house
mar
earth
mar (1) noun "earth" (world), also "home, dwelling, mansion". Stem mard- (VT46:13, PE17:64), also seen in the ablative Mardello "from earth" (FS); the word is used with a more limited sense in oromardi "high halls" (sg. oromar, PM17:64), referring to the dwellings of Manwë and Varda on Mt. Taniquetil (Nam, RGEO:66). The initial element of Mardorunando (q.v.) may be the genitive mardo (distinguish mardo "dweller"). May be more or less identical to már "home, house, dwelling" (of persons or peoples; in names like Val(i)mar, Vinyamar, Mar-nu-Falmar, Mardil) (SA:bar, VT45:33, VT47:6). Már is however unlikely to have the stem-form mard-; a "Qenya" genitive maren appears in the phrase hon-maren, q.v., suggesting that its stem is mar-. A possible convention could therefore be to use már (mar-) for "home, house" (also when = household, family as in Mardil, q.v.), whereas mar (mard-) is used for for "earth, world". Early "Qenya" has mar (mas-) "dwelling of men, the Earth, -land" (LT1:251); notice that in LotR-style Quenya, a word in -r cannot have a stem-form in -s-.
már
home, house, dwelling
már (mar-) (2) noun "home, house, dwelling" (also "house" in the sense of family as in Mardil, q.v.). See mar above for references. In Mar-nu-Falmar, Mardil, and as final element in Eldamar, Fanyamar, Valimar, Vinyamar..
cemi
earth, soil, land
cemi noun "earth, soil, land"; Cémi ("k")"Mother Earth" (LT1:257; the "Qenya" word cemi would correspond to cemen in LotR-style Quenya)
kemen
earth
kemen noun "earth"; see cemen.
mélamar
home
mélamar noun "home", Exilic Quenya word of emotional sense: place of ones birth or the familiar places from which one has been separated (PE17:109). Mélamarimma noun "Our Home", an expression used by Exilic Noldor for Aman.
Name of the first ruling steward of Gondor (LotR/670, 1039). Tolkien translated the name as “devoted to the house” (Let/386). It is a combination of mar(da) “house” and the suffix -(n)dil meaning “devoted to, -friend” (SA/bar, (n)dil).
Possible Etymology: In notes from the 1960s (PE17/106-7), Tolkien distinguished the word mar(da) (mard-) “house” and the word már “home” often used of the names of lands. The name Mardil might contain either, but I think marda “house” is more likely. Some authors have suggested that the “House” in this name may refer to the House (family) of the Kings of Gondor (QQ/már), but in Tolkien’s notes he said that these words were not used in this way (PE17/107).
Conceptual Development: This name first appeared in Lord of the Rings drafts from the 1940s as ᴹQ. Máraher the “Good Steward” but was quickly changed to ᴹQ. Mardil (WR/153).