Middle Primitive Elvish
oy
root. live, pass one’s days
oy
root. ever, eternal
geiā
adverb. ever
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.
A root in the Quenya Verbal System glossed “live, pass one’s days” with a Quenya verb ᴹQ. oi- of similar meaning (PE22/125). It might be a variant of √OY “ever”, though this root usually referred to “eternity” rather than a duration in time.