A Sindarin-only root in linguistic notes from 1959 meaning “go wrong, fail” with the basic sense of “miss mark, go (or send) wrong, fall short or beside ([one’s] aim, what is due or proper)” (PE17/151); in a marginal note Tolkien also wrote “go awry, ill, wrongly”. Its Quenya equivalent was √LOY.
Primitive elvish
loy
root. go wrong, fail, go wrong, fail, [ᴹ√] miss, fail to go; lack, be without
as’tāră
noun. faith, loyalty
sat(ar)
root. faithful, trust, loyal, rely, steadfast
satarŏ
noun. trusty follower, loyal companion
satrā
adjective. steadfast, trusty, loyal
dew
root. go wrong, fail
stor
root. steadfast
A root appearing Notes on Names (NN) from 1957 serving as an explanation for the element S. thorn “steadfast” in the name S. Arathorn, first appearing in a rejected page with variants √STOR and √THOR (PE17/113-114) and then later as only √THOR (PE17/113). This root may be connected to Q. torna “hard” in notes on Quenya intensive forms written between the first and second edition of The Lord of the Rings, where it was an element in Q. tornanga “hard iron”, with intensive forms aristorna, anastorna that imply derivation from √STOR (PE17/56).
Neo-Eldarin: For purposes of Neo-Eldarin, I would assume this root is √STOR to avoid conflict with ᴹ√THOR(ON), the basis for “eagle” words.
thor
root. steadfast
A Quenya-only root in linguistic notes from 1959 meaning “go wrong, fail” with the basic sense of “miss mark, go (or send) wrong, fall short or beside ([one’s] aim, what is due or proper)” (PE17/151); in a marginal note Tolkien also wrote “go awry, ill, wrongly”. Its Sindarin equivalent was √DEW. The root ᴹ√LOY also appeared in The Etymologies of the 1930s with the gloss “lack, be without; miss, fail to go”, though all of its derivatives were rejected (EtyAC/LOYO).