Middle Primitive Elvish
ata
root. father
atta
root. two
atta
cardinal. two
at
root. back, again, twice; two
atar
noun. father
atat
root. again, back
yatta
preposition. across
tata
root. two
atū
noun. father
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.