Qenya
téra
adjective. straight, right, straight, right, *correct
téna
adjective. straight, right
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.
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.
The Etymologies of the 1930s has ᴹQ. téra “straight, right” as a cognate to N. {tîr >>} taer, derived from {ᴹ✶tēra >>} ᴹ✶teñrā based on {ᴹ√TEƷ >>} ᴹ√TEÑ “line, direction” (Ety/TEƷ, TEÑ). Versions of the Lament of Atalante from the 1930s had téra “straight” as in malle téra “straight road” (LR/47, 56), but the version from the 1940s had téna “straight” (SD/310).
Conceptual Development: The Qenya Lexicon of the 1910s had ᴱQ. tea or taina “straight” under the early root ᴱ√TEHE “pull ?”, where the question mark was Tolkien’s (QL/90). Early Noldorin word-lists of the 1920s had ᴱQ. tína as a cognate to ᴱN. tain “straight”, both derived from ᴱ✶tegnā (PE13/153, 165).
Neo-Quenya: For purposes of Neo-Quenya, I would use téra “straight” as the best known form. I would also use téra to mean “right” = “✱correct” (not the direction “right”). For example, in response to the correct answer of a question you might say ta téra (ná) “that (is) straight” = “that is right/correct”. Saying á hilya i téra tie “follow the straight path” may also imply “follow the right/correct path”, depending on context.