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.
A (rejected) noun for “wolf” developed from the (rejected) root ᴹ√ƷARAM (Ety/ÑGARAM), most likely from primitive *✶ʒaramā [ɣaramā] given its cognates. It is an example of the Danian syncope, with second unstressed [a] vanishing after the identical vowel. It is also one of the Danian words for which a long final vowel developed into short final [a]. Finally, it provides an example of how [ɣ] became [g] in Danian.