A word appearing as Q. {tankil >>} tankal or tankala “clasp, brooch” in the second version of Tengwesta Qenderinwa (TQ2) from around 1950, derived from primitive ✶tankḷ or ✶tanklā respectively (PE18/100). Q. tañkal “brooch” also appeared in the contemporaneous Outline of Phonology (OP2) with a similar derivation (PE19/83). This word reflected Tolkien’s vision of the phonetic development of syllabic final ḷ in the 1950s and 60s, where syllabic ḷ developed a vowel of the same character as the preceding vowel, producing -al in this case.
Conceptual Development: The deleted form {tankil} from TQ2 hints at earlier developments for syllabic ḷ. The Etymologies of the 1930s had ᴹQ. tankil derived from ᴹ✶tankla “pin, brooch” under the root ᴹ√TAK “fix, make fast” (Ety/TAK). The first version of Tengwesta Qenderinwa (TQ1) from the 1930s instead had tankala “clasp, brooch”, but with tankil, tankḷ added in pencil (PE18/51 and note #51). The original layer of composition from the contemporaneous Outline of Phonetic Development (OP1) had tankila from ᴹ✶tanklā “fastener, brooch” with a variant tantya, but the primitive form was updated to ᴹ✶tanklă and the Quenya form to tañkal (PE19/40 and note #72). Thus the tankil forms reflects Tolkien’s original 1940s notion of the syllabification of ḷ to il (PE19/40 note #66), updated at some point to instead produce -al. In notes from 1969, Tolkien had ✶tanklă > Q. tankil (PE23/137), indicating he may have been considering restoring the 1940s system of syllabification.
The Qenya Lexicon and Poetic and Mythological Words of Eldarissa of the 1910s had an entirely unrelated form ᴱQ. pieksin for “brooch”, an elaboration of ᴱQ. piek “pin” (QL/73; PME/73).
Neo-Quenya: For purposes of Neo-Quenya I would use tancal only for a decorative brooch, and for “hasp, clasp” in clothing I would use [ᴹQ.] tangwa. Given 1969 tankil (PE23/137), the form tancil may be viable as well.
tanca ("k")adj. "firm, fixed, sure" (TAK)