Early Quenya
puhta
noun. coitus, *sex
pukta
noun. coitus, *sex
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 noun appearing as ᴱQ. puhta or pukta (the second possibly a primitive form) in Early Noldorin Word-lists of the 1920s as the cognate of ᴱN. hoith “coitus” (PE13/147, 163), probably derived from a variant form of the early root ᴱ√PU(HU) “generate” (QL/75).
Neo-Quenya: I would retain this word as ᴺQ. puhta “coitus, ✱sex” for purposes of Neo-Quenya based on a Neo-Root ᴺ√PUK for Elvish “sex” words.