A noun for “goblin” developed from primitive ᴹ✶orku, also attested in its plural form yrc (Ety/ÓROK). The change of [o] to [u] is hard to explain, as noted by Helge Fauskanger (AL-Nandorin/urc). In an earlier version of the entry Tolkien wrote Dan. orc (EtyAC/ÓROK), which is the expected form. The simplest explanation is that this form actually developed from a variant primitive form ✱✶urku. There is a similar issue with Ilk. urch, so perhaps this variant was used by those Eldar who did not complete the journey to Valinor.
Qenya
ork
noun. ork
orko
noun. goblin
A Doriathrin noun for “goblin” developed from primitive ᴹ✶orku, also attested in its plural form urchin (Ety/ÓROK). The change of [[ilk|[k] to [x] (“ch”) after the liquid [l]]] was a normal Ilkorin development, but the change of [o] to [u] is harder to explain, as noted by Helge Fauskanger (AL-Doriathrin/urch). In an earlier version of the entry Tolkien wrote Dor. orch (EtyAC/ÓROK), which is the expected form. The simplest explanation is that this form actually developed from a variant primitive form ✱✶urku. There is a similar issue with Dan. urc, so perhaps this variant was used by those Eldar who did not complete the journey to Valinor.