Early Quenya
rua
adjective. steady, still, tranquil
rúva
adjective. steady, still, tranquil
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!
An adjective appearing as ᴱQ. rua or rūva “steady, still, tranquil” in the Qenya Lexicon of the 1910s under the early root ᴱ√RU’U (QL/80).
Neo-Quenya: For purposes of Neo-Quenya, I would retain ᴺQ. rua “steady, still, tranquil” as a derivative of a Neo-Root ᴺ√RUH.