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.
isse
conjunction. where [relative]
númen endorello isse sí vaia síra
westward of Middle-earth where now Ocean flows
i
pronoun. that, what (relative pronoun)
elte
pronoun. he, *she, it (emphatic)
ette
pronoun. he, *she, it (emphatic)
inis
conjunction. where [relative]
is
conjunction. where [relative]
ista
noun. knowledge
istare
noun. knowledge
istya
noun. knowledge
masse
adverb. where
ye
preposition. at
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.
A correlative meaning “where” appearing in Demonstrative, Relative, and Correlative Stems (DRC) from 1948 (PE23/111), a combination of interrogative ᴹQ. ma and the locative suffix ᴹQ. -sse. It also appeared in several places in the Quenya Verbal System (QVS) from this same period (PE22/124-126). In DRC, it had a longer variant manas(se) based on mana “what” (PE23/111).