The root √AYA and its extended form √AYAN were associated with “holy” and “blessed” things all the way back in Tolkien’s earliest conception of the languages. It appeared as ᴱ√AY̯A “honour, revere” in the Qenya Lexicon of the 1910s with derivatives like ᴱQ. Ainu/Aini “god/goddess” and adjectives ᴱQ. aina or ᴱQ. aira “holy” (QL/34). Gnomish equivalents appeared in the contemporaneous Gnomish Lexicon such as G. ain “god” and adjectives aistog “holy” or †air(in) (GL/18).
The Etymologies of the 1930s gave this root as ᴹ√AYAN with very similar derivatives ᴹQ. Ainu, Aini and aina (Ety/AYAN), except Ainu/Aini was translated “holy one, angelic spirit (m./f.)” reflecting Tolkien’s evolving conception of his Legendarium. In this period there was an unaugmented variant ᴹ√YAN with the derivatives ᴹQ. yána/N. iaun “holy place” (Ety/YAN). It is not clear whether the short form √AYA was valid in this period; there is nothing like aira “holy”, for example.
The root √AYA and √AYA-N reappeared in etymological notes from the late 1950s, variously glossed “blessed” or “treat with awe/reverence” (PE17/147, 149). The (re)appearance Q. airë “holy, holiness”, Q. aira “holy”, and S. aer “holy” in later writing beside Ainu/Aini further support the reintroduction of the short form of this root.
Neo-Eldarin: For purposes of Neo-Eldarin, the continued use of the root √AYA in Tolkien’s later writing might be used to justify the restoration of a number of religious words derived from the early root ᴱ√AYA in the 1910s.