In Doriathrin it seems that a final [ð] (= “dh”) became [θ] (= “th”); a similar development occurred in Gnomish. The clearest example of this change is ᴹ✶rǭda > rōdh > Dor. rōth (Ety/ROD).

A more complex example is Dor. garth, whose cognates N. ardh and ᴹQ. arda imply a primitive form of [ɣarda] or [garda] (Ety/ƷAR). This means that first the [d] became [ð] after [r], and then developed into [θ] when it became final after the loss of the vowel. This change is more clearly indicated by the deleted Doriathrin form: garth (dh) (EtyAC/ƷARA). Helge Fauskanger also suggested this development (AL-Doriathrin/garth).

There are a few examples where this change did not occur: Ilk. erdh and Ilk. gwedh. It may be that this change only occurred in the Doriathrin dialect.