It seems that [w] was lost between an initial [k] or [g] and a following [o]. There is one example of this change for [kwo-]: ᴹ√KWAM > [kwāme > kwōm(e) >] côm (Ety/KWAM). For the case of [gwo-], the clearest example is archaic †gwo- “together”, for which Tolkien said: “in Ilk. owing to coalescence of gwo, ʒo (in go) this prefix was lost” (Ety/WŌ). The other examples of this rule involve an initial [w] becoming [gw], and then a resulting [gwo-] becoming [go-] (see below). This change was suggested by Helge Fauskanger (AL-Ilkorin/gôd, gôr, gwo-).