√NDAB/NDEB “endeavor, try, seek opportunity”
This is one of various roots that Tolkien considered for “try”. It first appeared as √NDEB in notes from around 1967, but Tolkien noted that this was “too obviously = endeavor”, and followed this with a new root √RIK “strive”, though √NDEB was not explicitly rejected (PE17/167). In Late Notes on Verbs (LVS) from 1969 Tolkien reintroduced a similar root √NDAB “endeavor, try, seek opportunity”, though without any derivatives (PE22/151). For purposes of Neo-Eldarin, I think √NDAB is problematic in that it collides with other forms, but √NDEB “try” might still be useful, perhaps with the nuance “*make an attempt, expirement” as opposed to √RIK “strive, *work towards, put forth effort”.
√NDAK “slay; hew”
This root and similar ones were the basis for “slay” words for much of Tolkien’s life. The root first appeared in the Early Qenya Phonology of the 1920s as ᴱ√dag- with numerous etymological variants, including ᴱQ. taila/ᴱN. dail “axe (blade)” < dagla, ᴱQ. tanga-/ᴱT. danga- “to beat” < tang-, and ᴱQ. nahta-/ᴱN. dag- “to slay” (PE14/65-66); these last two words for “slay” appeared regularly in Tolkien’s writings thereafter. The root reappeared as ᴹ√NDAK “slay” in The Etymologies of the 1930s with similar Noldorin derivatives (Ety/NDAK), apparently a strengthened form of ᴹ√DAK “slay” (EtyAC/DAK).
The root was given as ᴹ√NDAG “slay” in the Quenya Verbal System of the 1940s (PE22/102, 115), but unglossed ᴹ√NDAK appeared in the same document (PE22/112), and verb ᴹQ. nak- was sometimes glossed “kill” as well (PE22/120). The root appeared as √NDAK “hew, slay” in the Outline of Phonology from the 1950s (OP2: PE19/91) and again as √NDAK “hew” in Late Notes on Verbs from 1969 (LVS: PE22/156). This introduction of the sense “hew” in the 1950s and 60s may be a partial restoration of the senses of the 1920s root ᴱ√dag-, which meant more that just “slay”. If so, √NDAK may be compared with √MAK which had a similar variety of meanings (“cleave, sword, slay, fight, forge”); see that entry for details.
√(N)DAN “back (again), [ᴹ√] backwards; [√] retreat, go back, give way (as one advances), revert”
The most notable use of the root √(N)DAN “back(wards)” was in the name Q. Nandor for those Elves who joined in the march to Valinor but turned back during the journey (VT48/32); the same root was an element in the earlier name for the Nandor from the 1930s, the Danas (Ety/NDAN). The root first appeared as ᴹ√NDAN “back” in The Etymologies of the 1930s with derivatives like the aforementioned Danas as well as the prefix ᴹQ. nan- “backwards” and the Doriathrin noun dôn “back” (Ety/NDAN). The Etymologies also mentioned an unstrengthened form of the root ᴹ√DAN (Ety/DAN).
The root √(N)DAN appeared several times in Tolkien’s later writings. It appeared among a list of roots having to do with “back” probably composed around 1959 (PE17/166). In this list, Tolkien clarified that in Quenya, √NDAN specifically meant “back” as an action by the same agent revising a previous action, as opposed to an action by a different agent, for which Tolkien coined the root {√TŌ/OTO >>} √KHAN; the example Tolkien gave was Q. nanwen-/S. dadwen- “return, go back [by same agent]” < √NDAN vs. {{Q. tóquet- >>} Q. hanquenta “answer [by a different agent]”. This distinction was lost in Sindarin, however, and √NDAN came to be used for both same and differing agents. Tolkien also said that √NDAN could be used “of return (in same path), retracing, and so employable as un- as in undo”.
The root was mentioned again in the Quendi and Eldar essay from 1959-60, where Tolkien said:
The name Nandor was a derivative of the element *dan, *ndan- indicating the reversal of an action, so as to undo or nullify its effect, as in “undo, go back (the same way), unsay, give back (the same gift: not another in return)”. The original word *ndandō, therefore, probably only implied “one who goes back on his word or decision”.
Finally, the root appeared in some notes from the late 1950s where √dan- was glossed “retreat, go back, give way (as one advances), revert” serving as the basis for {✶danmi >>} ✶ndanmē > Q. nanwë/S. dannen “ebb-tide”, apparently originally meaning “retreat” (VT48/26 author’s note #2, VT48/32 editor’s note #18). In the same document Tolkien again mentioned the connection of this root to the name of the Nandor.
√N(D)ER “male (person), man”
This root and ones like it were the basis for Elvish “man” words for much of Tolkien’s life. The earliest form of this root was ᴱ√NERE with derivatives like ᴱQ. ner “man, husband” and ᴱQ. nertu “strength” (QL/65). The latter had a cognate G. nert in contemporaneous Gnomish Lexicon, along with a set of related “strength” words (GL/60). But Gnomish also had a set of derivatives based on the elided primitive form ᴱ✶n’reu̯ such as G. †drio “hero” and driog “valiant” (GL/30). Derivatives with an initial n- continued to appear in Early Noldorin word lists from the 1920s, such as ᴱN. †nîr “hero, prince” and ᴱN. ne(i)rion “hero” (PE13/164).
In The Etymologies of the 1930s, the base root was ᴹ√DER “adult male, man (of any race)” with strengthened variant ᴹ√NDER “bridegroom”, but with the Quenya root becoming ᴹ√NĒR “man” under the influence of ᴹ√NĪ “woman” (Ety/DER, NDER, NĒR, NĪ); from this point forward Noldorin/Sindarin derivatives began with d-, such as S./N. dîr “man”. However, in the first version of Tengwesta Qenderinwa from this same period, the primitive root is given as ᴹ√NER “man” (TQ1: PE18/35). On the other hand in Quendian & Common Eldarin Verbal Structure, also from the late 1930s, the root was given as ᴹ√(N)DER “man, male”, again as a strengthening of ᴹ√DER (EVS1: PE22/98).
Starting in the 1950s, Tolkien was more consistent in making the base root √NER with strengthened form √NDER. Tolkien gave √NDER/NER “male person” in Common Eldarin: Verb Structure (EVS2: PE22/133) and Common Eldarin: Noun Structure (PE21/70), both from the early 1950s. In the Quendi and Eldar essay from 1959-60 the base root was √NERE, though Tolkien clarified that the base root as referred more specifically to “physical strength and valour” (WJ/393). The root is given as √NER “man, male” in notes from the late 1960s (VT47/33).
ᴹ√(N)DEW “follow, come behind”
A root in The Etymologies of the 1930s glossed “follow, come behind”, apparently a strengthened form of ᴹ√DEW (Ety/NDEW; EtyAC/DEW). Its most notable derivative is Doriathrin name Dior “successor”, name of Thingol’s grandson and heir after the departure of his parents Beren and Lúthien. This name dates back to the earliest versions of the Legendarium, and Tolkien continued to use it in later versions of the Silmarillion, but this is the only place he gave it a derivation. However, Dior cannot be a derivative of √NDEW in Sindarin, since [eu] became [iu] and then became [ȳ] (VT47/7), so that the result would be *dŷr in Sindarin. Most likely Dior was one of those names Tolkien retained from the earliest iteration of the Legendarium despite it no longer having any clear etymological foundation in later versions of the Elvish languages.