Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!

Qenya 

yatta

noun. narrow neck, isthmus, (narrow) neck, isthmus; *(lit.) joining

A word for “narrow neck, isthmus” in The Etymologies of the 1930s (Ety/YAK). Although Christopher Tolkien presented ᴹQ. yatta as if it were a derivative of ᴹ√YAK (LR/400), in their Addenda and Corrigenda to the Etymologies Carl Hostetter and Patrick Wynne indicated it was actually a derivative of a deleted root ᴹ√YATH, that appeared between ᴹ√YAK and ᴹ√YAT “join” (VT46/22). Although ᴹ√YATH was deleted, ᴹQ. yatta was not, and it was possible Tolkien reconceived of it as a derivative of ᴹ√YAT, as suggested by Hostetter and Wynne. As for ᴹ√YAK, Tolkien had a similar word ᴹQ. yat (yaht-) “neck” derived from that root.

Conceptual Development: In the Qenya Lexicon of the 1910s, Tolkien had ᴱQ. yatta “neck, also isthmus” under the early root ᴱ√ẎATA “join”, along with an archaic variant †yat (QL/105). In a list of body parts from the 1920s, Tolkien instead had ᴱQ. yat (yakt-) “neck” (PE14/117).

Neo-Quenya: It is not clear that both yaht- and yatta should coexist. For purpose of Neo-Quenya, I would just use yatta “(narrow) neck, isthmus”, as it has a clearer etymology and ᴹ√YAT has a larger set of derivatives.

Derivations

  • ᴹ√YAK “*neck” ✧ Ety/YAK
  • ᴹ√YAT “join” ✧ EtyAC/YAK

Phonetic Developments

DevelopmentStagesSources
ᴹ√YATH > yatta[yatʰtā] > [yattʰā] > [yattā] > [yatta]✧ EtyAC/YAK
Qenya [Ety/YAK; EtyAC/YAK] Group: Eldamo. Published by

yat

noun. neck, neck; [ᴱQ.] isthmus

Cognates

  • N. iaeth “neck” ✧ Ety/YAK

Derivations

  • ᴹ✶yakta- “neck” ✧ Ety/YAK
    • ᴹ√YAK “*neck” ✧ Ety/YAK

Phonetic Developments

DevelopmentStagesSources
ᴹ✶yakta- > yat[jakta] > [jakt] > [jaxt] > [jat]✧ Ety/YAK

Variations

  • yat ✧ Ety/YAK