An unglossed root in a rejected paragraph from the Quenya Verbal System of the 1940s (PE22/112 note #78).
Middle Primitive Elvish
lop
root. horse, horse; [ᴱ√] *run (of animals), gallop, lope
lopō
noun. rabbit
lopōtundu
noun. rabbit hole
auluta-
verb. [unglossed]
bay
root. [unglossed]
iw
root. [unglossed], [ᴱ√] *fish
kaltwa
?. [unglossed]
khlip
root. [unglossed]
kōmā
noun. [unglossed]
maiga
root. [unglossed]
An unglossed root appearing in the first version of Tengwesta Qenderinwa from the 1930s (TQ1) to illustrate certain patterns of root formation (PE18/66). It may have serving as the basis for ᴹQ. Maia, though this word was given different derivations later.
phan
root. [unglossed]
A deleted root in The Etymologies of the 1930s with no glosses or derivatives and no clear function (EtyAC/PHAN).
skil
root. [unglossed]
A root mentioned in passing in as a variant of ᴹ√KIL “divide” in The Etymologies of the 1930s, but it had no derivatives and appeared nowhere else (Ety/KIL).
stin
root. [unglossed]
stā
root. [unglossed]
torōmā
noun. [unglossed]
uruk
root. [unglossed]
A root in The Etymologies of the 1930s with no glosses or derivatives and no clear function (EtyAC/URUK).
us
root. [unglossed]
A root in The Etymologies of the 1930s with no glosses or derivatives and no clear function (EtyAC/US).
This root was the basis for horse words starting with the Qenya Lexicon of the 1910s, where it appeared unglossed as ᴱ√LOPO (QL/56). It was compared to the root ᴱ√LOQO, and these roots include the verbs ᴱQ. lopo- “gallop, run (of animals)” and ᴱQ. loqo- “run (of human beings)”, so I think it is likely those were the meanings of the roots as well (QL/56). In the Qenya Lexicon, ᴱ√LOPO had the derivatives ᴱQ. lōpa “horse or mare” and ᴱQ. lopsi “mare” (QL/56), but elsewhere in that document there was the word ᴱQ. lapatte “rabbit” < ᴱ✶lopatte, so I think that word is related as well, though Tolkien did mark the primitive form with a “?” (QL/51). The probably-related word ᴹQ. lopo “rabbit” appeared in a discussion of nouns from the early 1930s (PE21/31).
In The Etymologies of the 1930s the root ᴹ√LOP was glossed “horse”, and its derivatives ᴹQ. olombo and N. lobor had only that sense (EtyAC/LOP), but horse words were usually derived from ᴹ√ROK from the 1930s and later. The word Q. lopoldi “rabbits” appeared in some 1965 notes on Númenor, so It seems likely √LOP remained valid in some form. Another possibly related late word is S. ✱laba- “hop” as in S. Labadal “Hopafoot” (UT/60).
Neo-Eldarin: For purposes of Neo-Eldarin, I think it is worth retaining ᴹ√LOP with a verbal sense “✱gallop, lope”. In this way, it can remain the basis for rabbit words based on their loping run. The horse words from this root might be specialized for heavier loping horses like destriers, since ᴹQ. rokko was said to refer more specifically to a “swift horse” (EtyAC/ROK).