The root ᴹ√EREK appeared in The Etymologies of the 1930s with the gloss “thorn” and derivatives meaning “prick” or “holly” in both Quenya and Noldorin (Ety/ERÉK). Elsewhere in the document it appeared in its unaugmented form ᴹ√REK (EtyAC/REK). It was the basis of the two names Ilk. Region and N. Eregion “Hollin”. The continued appearance of these names in the Legendarium indicates the continued validity of these roots.
Middle Primitive Elvish
thor(on)
root. come swooping down
(e)rek
root. thorn, holly
ek
root. spear, (sharp) point, thorn
thaurēnā
adjective. *fenced
gais-
verb. to dread
a-
prefix. complete
makla
noun. sword
Tolkien used similar Elvish words for “eagle” for much of this life. The first appearance of its root was ᴱ√ŠORO⁽⁾ “eagle” from the Qenya Lexicon of the 1910s with derivatives like ᴱQ. sorne “eagle” and ᴱQ. sornion “eyrie” (QL/86). Gilson, Hostetter, Wynne and Smith suggested that the Š may represent more ancient Þ, and Gnomish derivatives from the contemporaneous Gnomish Lexicon such as G. thorn “eagle” and G. thrond “eyrie, pinnacle” confirm that the actual early root was ✱ᴱ√ÞORO (GL/73). In The Etymologies of the 1930s Tolkien gave the root as ᴹ√THOR or ᴹ√THÓRON “come swooping down” with derivatives like ᴹQ. soron/N. thoron “eagle” and N. thôr “swooping, leaping down” (Ety/THOR). In a 1972 letter to Richard Jeffery, Tolkien gave primitive form ✶thorono “eagle” as the basis for Q. sorno/S. thoron, testifying to the enduring nature of this root (Let/427).