An empty land south of Gondolin (S/121), apparently meaning “✱Sad Home”, a combination of dem “sad(ness)” (stem form dimb-) and bâr “home” (SA/bar).
Conceptual Development: The name Dimbar first appeared Silmarillion drafts from the 1930s (LR/261), and was given in The Etymologies as an Ilkorin name with the derivation described above (Ety/DEM), though the exact language of word dem is unclear; see that entry for further discussion.
Tolkien continued to used Dimbar in his Silmarillion revisions from the 1950s-60s (WJ/57), so he may have intended this Ilkorin name to become Sindarin, though it is also possible he would have eventually would have revised the name to something else.
dimb (Ilk. “sad, gloomy” [Etym. DEM-]) + (m-)bar (“land, dwelling”)