√KYAW root. “taste, select, choose”
This root and ones like it were connected to taste throughout Tolkien’s life. The earliest manifestion of this root was ᴱ√TYAVA “to savour, taste” with derivatives like ᴱQ. tyausta “savour, flavour” and ᴱQ. tyava- “it tastes of, reminds one of” (QL/49); in the contemporaneous Gnomish Lexicon it had derivatives like G. caf- “to taste” and G. côf “savour, smack, odour” (GL/24).
In The Etymologies of the 1930s the root became ᴹ√KYAB “taste” with a derivative ᴹQ. tyav- of the same meaning (Ety/KYAB). This root and verb also appeared in the Quenya Verbal System of the 1940s (PE22/102). The root appeared again in Late Notes on Verbs from 1969, first as √KJABA “taste”, then as √KJAW “taste, select, choose”, the latter with derivatives Q. tyav- and S. caw- “taste” (PE22/151, 152).
For purposes of Neo-Eldarin, I recommend assuming the root was √KYAW, since some of the later derivatives like S. caw- can only be derived from this version of the root.
References ✧ PE22/151-152
ᴹ√KYAB root. “taste”
References ✧ Ety/KYAB; PE22/102
ᴱ√TYAVA root. “to savour, taste”
References ✧ GL/24; QL/49