An adjective in The Etymologies of the 1930s glossed “long (and thin)” derived from the root ᴹ√TAY “extend, make long(er)” (Ety/TAY).
Noldorin
taen
noun. height, summit of high mountain
taen
adjective. long (and thin)
taen
adjective. long (and thin)
taen
noun. height, summit of high mountain
taen-nimdil
place name. Taen-Nimdil
anann
adverb. long
ann
adjective. long
ann
adjective. long
gammas
noun. s-sign (special sign used to mark a final -s in Tengwar)
A noun in The Etymologies of the 1930s glossed “height, summit of high mountain” derived from primitive ᴹ✶taʒna of similar meaning (Ety/TĀ), where the diphthong ae arose due to the usual [[n|vocalization of ʒ [ɣ] before nasals]]. It would have gone through the same vocalizations and had the same form if it were a Sindarin word.
Conceptual Development: In Early Noldorin Word-lists there were two similar nouns: ᴱN. tain “mountain” (PE13/153) and ᴱN. dain “height, summit; height, loftiness, sublimity” (PE13/141, 161). The first of these probably had a derivation similar to later N. taen, but the latter was derived from primitive ᴱ✶dágniya. The two forms seems to represent distinct early roots ✱ᴱ√DAHA and ᴱ√TAHA, which would have blended together in Early Qenya since initial voiced stops were unvoiced: d- > ᴱQ. t-.