A word that technically means “spark”, but was often applied to stars as well (PE17/66, RGEO/61), derived from the root √TIN “spark(le)” (MR/388; PE17/22).
Conceptual Development: ᴱQ. tinwe was used for “star” all the way back in the Qenya Lexicon of the 1910s, where it was also derived from the root ᴱ√TINI “twinkle” (QL/92). In The Etymologies of the 1930s it appeared as ᴹQ. tinwe “spark (star)” with the primitive form ᴹ✶tinmē under the root ᴹ√TIN “sparkle, emit slender (silver pale) beams” (Ety/TIN); the gloss was corrected from “sparkle (star)” to “spark (star)” by Carl Hostetter and Patrick Wynne in their Addenda and Corrigenda to the Etymologies (EtyAC/TIN). The word and its derivation appeared numerous times in Tolkien’s later writings, making it exceptionally stable in his mind.
tinwë noun "spark" (gloss misquoted as "sparkle" in the Etymologies as printed in LR, see VT46:19), also "star"; pl. tinwi "sparks", properly used of the star-imagines on Nur-menel (q.v.). Cf. nillë. (TIN, MR:388) In early "Qenya", tinwë was simply glossed "star" (LT1:269, cf. MC:214). In one late source, the meaning of tinwë is given as "spark", and it is said that this word (like Sindarin gil) was used of the stars of heaven "in place of the older and more elevated el, elen- stem" (VT42:11).