A noun in The Etymologies of the 1930s appearing as car or carð with the gloss “house” under the root ᴹ√KAR “make, build, construct” (Ety/KAR). Its Quenya cognate ᴹQ. kar (kard-) was glossed “building, house”.
Neo-Sindarin: Given the meaning of its root, I would use cardh for any kind of building-like construction or structure for purposes of Neo-Sindarin. For an ordinary “house” where people live, I would use S. bâr.
A transient name for Osgiliath appearing in Lord of the Rings drafts from the 1940s (TI/424), a combination of ost “town” and echain “built again”.