An unglossed root in the Qenya Lexicon of the 1910s whose derivatives had to do with tickling such ᴱQ. kitya- “tickle” and ᴱQ. kityalea “ticklish, susceptible, sensitive” (QL/47). The contemporaneous Gnomish Lexicon contained a couple of possible Gnomish cognates: G. tisc “ticklish” and G. tisca- “tickle” (GL/70). This kind of k/t variation is seen in a few other early Qenya and Gnomish forms, such as ᴱQ. talqe “glass” vs. G. celc (QL/88; GL/25) and probably represents variant roots in ancient Elvish.
I think it is worth preserving this root for purposes of Neo-Eldarin, but the only way I see to preserve a similar k/t variation in the phonetic systems of later Quenya and Sindarin is to posit a root inversion to √TIK in the Sindarin branch, as in the inversion of the CE root √LED’s to √DEL in Quenya (WJ/363).
Tolkien gave the roots √KIN and √KIT with the gloss “small” in Notes on Names (NN) from 1957; given Sindarin derivative S. cidinn, √KIT is the likelier of the two possibilities (PE17/157).
Neo-Eldarin: For purposes of Neo-Eldarin, I recommend against using the Quenya derivative of this root, as there are other better-known Quenya words for “small”. In Sindarin, however, we have fewer options, and I think it is worth retaining this root for that branch of the Eldarin languages.