Dan. Dior m.
In The Etymologies from the 1930s, Tolkien first marked the name Dior as both Doriathrin and Ossiriandic (EtyAC/NDEW). He then changed the name so that it was only Doriathrin, perhaps because the diphthong [io] did not appear until very late in Ossiriandic.
Reference ✧ EtyAC/NDEW ✧ Oss. Dior
|ᴹ✶ndeuro > Dior||[ndeurō] > [ndeur] > [deur] > [deor] > [dior]||✧ EtyAC/NDEW|