OKO is a Primitive Quendian root signifying "wicked, evil".
The root is one of the opposites of AYA.
 See also
- ↑ 1.0 1.1 1.2 J.R.R. Tolkien, "Words, Phrases and Passages in Various Tongues in The Lord of the Rings: Eldarin Roots and Stems", in Parma Eldalamberon XVII (edited by Christopher Gilson), p. 149 (root appearing as "OKO")