This root was the basis for Elvish words having to do with “running” and (in earlier notes) “rolling” for much of Tolkien’s life. It first appeared as ᴱ√NORO “run, go smoothly, ride, spin” in the Qenya Lexicon of the 1910s (QL/67), and it had derivatives in the contemporaneous Gnomish Lexicon like G. nor- “run, roll” (GL/61) as well as dronn “race, course, track” < ✱n’rond- (GL/31). ᴹ√NORO “run as of wheels, roll along” reappeared in a page of roots in the Quenya Verbal System of the 1940s, though this page was deleted (PE22/127 note #152). √NOR “run (or leap: of animals, men etc.)” also appeared in some etymological notes associated with The Lord of the Rings, probably from the late 1950s (PE17/168).
Neo-Eldarin: For purposes of Neo-Eldarin, I’d retain both senses “run” and “roll” for this root, but limit the latter to the rolling of wheels as an extrapolation from the movement of legs.
Tolkien had Elvish “hair” words that began with fin- for most of his life, but the details of their derivation evolved. The earliest form of this root was unglossed ᴱ√FIÐI [FIÐI] in the Qenya Lexicon of the 1910s with derivatives like ᴱQ. findl “lock of hair” and ᴱQ. firin “ray of sun” (QL/38). It also had derivatives in the contemporaneous Gnomish Lexicon such as G. fiðra “collective hair” and {findel >>} G. finn “a lock of hair” (GL/35), the latter an element in the name G. Glorfindel “Golden Hair”, a name that retained this form and meaning for all of Tolkien’s life.
In The Etymologies of the 1930s Tolkien had unglossed ᴹ√SPIN with derivatives like ᴹQ. finde “tress, braid of hair” and N. finnel “(braided) hair” (Ety/SPIN). He made a point that this root was distinct from ᴹ√PHIN “nimbleness, skill” (Ety/PHIN), a distinction he reemphasized in later writings as well (PE17/17, 119). The additional form ᴹQ. fine “larch” (a species of tree with needle-like leaves) indicates the 1930s root was not limited exclusively to “hair” (Ety/SPIN). The root √SPIN appeared a number of times in Tolkien’s later writings, variously glossed “single hair, filament” >> “fine thread, filament” (PE17/17), “lock, tress of human/elvish hair” as extended √SPIN-ID (PE17/119), or “single hair” (PE17/185). However, in The Shibboleth of Feanor from 1968 Tolkien gave the root as √PHIN “hair” (PM/340).
Neo-Eldarin: For purposes of Neo-Eldarin, I would ignore this 1968 change of √SPIN >> √PHIN. Furthermore, I would assume √SPIN referred to a single hair or other kind of filament, and extended √SPINID referred to a tress of hair.