There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.

Qenya 

teren

adjective. slender, slender; [ᴱQ.] lissom, lithe

An adjective appearing as teren or terene “slender” in The Etymologies of the 1930s, derived from ᴹ✶terēn(ē) under the root ᴹ√TER “pierce” (Ety/TER). The Qenya Lexicon of the 1910s had ᴱQ. teren “lissom, lithe” under the early root ᴱ√TEŘE [TEÐE] also having to do with piercing, but Tolkien marked ᴱQ. teren with a “?” (QL/91).

terendul

masculine name. Slender and Dark

Another name for Herendil in Tolkien’s unfinished story “The Lost Road”, translated “Slender and Dark” (LR/59). In The Etymologies, the name was glossed “slender-dark” given as a compound of teren “slender” and the root ᴹ√(N)DUL, which had derivatives such as nulla “dark” (Ety/DUL, NDUL, TER).

Qenya [Ety/DUL; Ety/NDUL; Ety/TER; EtyAC/DUL; LR/059; LRI/Terendul] Group: Eldamo. Published by

terene

adjective. slender

ninde

adjective. slender, slender, *thin

A word for “slender” in The Etymologies of the 1930s under the root ᴹ√NIN-DI “fragile, thin” (Ety/NIN-DI).

Neo-Quenya: For purposes of Neo-Quenya, I would also use this word for “✱thin” based on the meaning of its root.


Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.