The root √OKO was mentioned a couple times in Definitive Linguistic Notes (DLN) from 1959 with glosses like “wicked, evil” and “evil, bad” serving as the basis for Q. olca/S. ogol “bad, wicked, evil” along with similar words (PE14/149, 170). In other notes from this period Tolkien said √OKO “evil” influenced the meaning of the Sindarin root √AK “hostile return” (PE17/167). In one of these 1959 notes, Tolkien wrote UK, UKLA below OKO with derivatives Q. ulca and S. ogl, all unglossed (PE17/149); Q. ulca was the word Tolkien used most frequently for “evil” in Quenya. In notes from 1968, Tolkien mentioned √UK “nasty” in passing, without giving any derivatives (VT48/25); Patrick Wynne suggested this form of the root may have been connected to 1969 √UG “dislike” (VT48/32 note #15; PE22/160).
Neo-Eldarin: For purposes of Neo-Eldarin, I prefer Q. ulca for “evil”, but I think √OKO “wicked” might coexist with it as variant to salvage other words from that root.
The root √OKO was mentioned a couple times in Definitive Linguistic Notes (DLN) from 1959 with glosses like “wicked, evil” and “evil, bad” serving as the basis for Q. olca/S. ogol “bad, wicked, evil” along with similar words (PE14/149, 170). In other notes from this period Tolkien said √OKO “evil” influenced the meaning of the Sindarin root √AK “hostile return” (PE17/167). In one of these 1959 notes, Tolkien wrote UK, UKLA below OKO with derivatives Q. ulca and S. ogl, all unglossed (PE17/149); Q. ulca was the word Tolkien used most frequently for “evil” in Quenya. In notes from 1968, Tolkien mentioned √UK “nasty” in passing, without giving any derivatives (VT48/25); Patrick Wynne suggested this form of the root may have been connected to 1969 √UG “dislike” (VT48/32 note #15; PE22/160).
Neo-Eldarin: For purposes of Neo-Eldarin, I prefer Q. ulca for “evil”, but I think √OKO “wicked” might coexist with it as variant to salvage other words from that root.