A word for “circle” in Early Noldorin word-lists of the 1920s derived from primitive ᴱ✶kṛkta (PE13/140).
Early Noldorin
crithos
noun. ring, ring; [G.] circle
craith
noun. circle
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 Gnomish Lexicon of the 1910s had G. crithos “a circle” (GL/27). Gnomish Lexicon Slips modifying that document glossed crithos as “a circle, ring” (PE13/111), while Early Noldorin word-lists of the 1920s had ᴱN. crithos “a ring”.