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 

tyulusse

noun. poplar-tree

A word for a “popular-tree” in The Etymologies of the 1930s derived from primitive ᴹ✶tyulussē under the root ᴹ√TYUL “stand up (straight)” (Ety/TYUL). ᴱQ. tyulusse “poplar” also appeared several times in Tolkien’s writings in the 1910s and 20s, already derived from the early root ᴱ√TYULU (QL/50; PME/50; PE16/139).

Conceptual Development: See the root ᴹ√TYUL for a discussion of later evolutions of its primitive forms.