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”. Likewise 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). However, in the first version of Tengwesta Qenderinwa from the 1940s, the primitive root is given as ᴹ√NER “man” (TQ1: PE18/35) and likewise from the first version of Quenya Personal Pronouns from the late 1940s (QPP1: PE23/87).
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).
This root, the basis for the word “one”, was established early and retained its meaning throughout Tolkien’s life. It appeared all the way back in the Qenya Lexicon of the 1910s as ᴱ√ERE “remain alone”, and was the basis for ᴱQ. er “one” and ᴱQ. eressea “lonely” (QL/36). These words retained their forms and meaning for the entirety of Tolkien’s life, most notably in Q. Tol Eressëa “Lonely Isle” whose form and meaning were likewise introduced very early and never changed.
The contemporaneous Gnomish Lexicon also had a variety of words derived from this root, such as G. er “one” and G. ereth “solitude” (GL/32). This root appeared in The Etymologies of the 1930s as ᴹ√ERE “be alone, deprived” with both Quenya and Noldorin derivatives (Ety/ERE). The root continued to appear in Tolkien’s later writings, variously glossed as “one”, “single”, “alone”, or “only”.
One interesting feature of this root was the limitations of its use as a number. In some 1968 notes on river names Tolkien said:
> [S.] Erui. Though this was the first of the Rivers of Gondor it cannot be used for “first”. In Eldarin er was not used in counting in series: it meant “one, single, alone” (VT42/10).
In accompanying notes, Tolkien gave:
> 1 “single” (non-serial) ER; “one, first of a series” MIN (VT42/24).
Thus the root for “one” when counting the first of a series was √MIN, whereas √ER could only be used of things that were isolated or unique.