This root was established as the basis for “four” very early, though the earliest known Elvish word for “four” was actually ᴱQ. nelde from the Qenya Lexicon of the 1910s (QL/65), which became “three” later on (PE14/49). In the Gnomish Lexicon written soon after, the Gnomish word for “four” was G. cant (GL/25), and by the Early Qenya Grammar of the 1920s, the Qenya word likewise became ᴱQ. kanta “four” (PE14/49, 82). The Quenya word kept this form thereafter, and the Noldorin form became N. canad in The Etymologies of the 1930s, where the root ᴹ√KANAT “four” explicitly appeared for the first time (Ety/KÁNAT). The words and root for “four” remained the same thereafter (VT42/24-26; VT47/15-16; VT48/10), with occasional minor (and transient) variations such as √KENET (VT47/41).
Primitive elvish
-tā
suffix. verb suffix (transitive), causative
-tă
suffix. verb suffix (intransitive)
tata
masculine name. Two
māīta
?. māīta
tā/taʒ
root. high, high, [ᴹ√] lofty; noble
-ta
suffix. noun suffix, single product of an action
abta-
verb. refuse, deny, say no
atata
root. two, two; [ᴹ√] again, back
bāta-
verb. to ban, prohibit, refuse, forbid
ista-
verb. to know
khotta
verb. gather hastily together, pile up
orta-
verb. to rise, ascend
(a)tata
cardinal. two
atta
cardinal. two
amtā
noun. amtā
san-
pronoun. that
ektā-
verb. prick with a sharp point, stab
ṃbart(ă)
noun. fate, doom; (orig.) permanent establishment
kelutā-
verb. to cause to spring forth, start (water) flowing, tap
mal(a)tā Reconstructed
noun. gold (as metal)
kanat
root. four
ent(h)a
pronoun. away over there, in time to come
hektā-
verb. set aside, cast out, forsake
oktā
noun. war, hostility, strife
tektā
noun. sign, symbol, mark
tāra
adjective. high
-(s)tā
suffix. -(s)tā
-yā
suffix. causative
-yă
suffix. formative
aba-
verb. refuse, forbid
amtā-
verb. to enlarge, increase
an
preposition. to
imte
pronoun. themselves
kanatā
cardinal. four
magtā-
verb. to handle, wield, manage, deal with
nō
adverb. behind
orya-
verb. to rise
pal’tā
verb. to feel with the hand, stroke
satya-
verb. set aside
te
pronoun. they
tī
pronoun. they
This root and ones like it were used for “high” things for much of Tolkien’s life. It first appeared as unglossed ᴱ√TAHA in the Qenya Lexicon of the 1910s with derivatives like ᴱQ. tā “high; high above, high up”, ᴱQ. tahōra or tayóra “lofty”, and ᴱQ. tāri “queen”; it had a variant form ᴱ√TAʕA where the ʕ might be a malformed Y (QL/87). The corresponding forms in the contemporaneous Gnomish Lexicon were G. dâ “high” and G. dara “lofty” (GL/29), indicating the true form of the root was ᴱ√DAHA, since initial voiced stops were unvoiced (d- > t-) in Early Qenya (PE12/17). Primitive forms like ᴱ✶dagá > ᴱN. dâ/ᴱQ. tá “high” in Early Noldorin Word-lists of the 1920s indicates the root continued to begin with D for the following decade (PE13/141, 161).
In The Etymologies of the 1930s Tolkien gave this root as ᴹ√TĀ/TAƷ “high, lofty; noble” with derivatives like ᴹQ. tára “lofty, high”, ᴹQ. tári “queen” and N. taen “height, summit of high mountain” (Ety/TĀ). In Definitive Linguistic Notes (DLN) from 1959 Tolkien gave the root as √TAG or Tā- “high”, and in notes from around 1967 Tolkien gave √TAƷ as the explanation of the initial element of Q. Taniquetil and contrasted it with √TĂR “stand” (PE17/186). In 1970 green-ink revisions to the Outline of Phonology (OP2), Tolkien wrote a marginal note giving √TAƷ > TĀ “high”, but this note was rejected with a statement “transfer to Gen. Structure. No [ʒ] existed in Eldarin” (PE19/72-73 note #22).
This last rejection seems to be part of Tolkien’s general vacillation on the nature and phonetic evolution of velar spirants in Primitive Elvish in 1968-70. For purposes of Neo-Eldarin, I would assume the root form was √TAH or √TAƷ > √TĀ as the basis for “high” words, much like √MAH or √MAƷ > ✶mā was the basis for “hand” words.