ᴹ√SALAP root. “lick up, *sip”
The first iteration of this root was unglossed ᴱ√SḶPḶ in the Qenya Lexicon of the 1910s with derivatives like ᴱQ. salpa “bowl” and ᴱQ. sulp- “lick, sup, lick up, sup up” (QL/84). It also had derivatives in the contemporaneous Gnomish Lexicon such as G. salf “bowl, basin” (GL/66), as well as G. thlib- “sup, lap up, suck” (GL/73). Later versions of these verb forms appeared in Early Noldorin Word-lists of the 1920s as ᴱN. lhif “drinks” and ᴱQ. sulpe “sips, tastes” from primitive ᴱ✶slp- along with (unused) variant ᴱ✶slq- (PE13/148-9). The verb ᴱQ. sulpe “drinks” was also mentioned in the Early Qenya Grammar of the 1920s, again as a derivatives of sḷp- (PE14/58).
In The Etymologies of the 1930s, the root reappeared as ᴹ√SALAP “lick up” with derivatives ᴹQ. salpa- “lick up, sup, sip” and N. salff “broth” (Ety/SÁLAP; EtyAC/SÁLAP). But in the Quenya Verbal System of the 1940s Tolkien had the TALAT-stem verb ᴹQ. sulpa- “to lap up, drink greedily” (PE22/114), hinting at a root *ᴹ√SULUP. Assuming ᴹ√SALAP and ᴹ√SULUP coexisted, they must have been etymological variants, since the vowel variations that resulted from primitive syllabic ḷ were no longer a feature of Elvish.
Neo-Eldarin: For purposes of Neo-Eldarin, I’d use √SALAP = “sip” and √SULUP = “lap”.
Reference ✧ Ety/SÁLAP ✧ SÁLAP “lick up”
ᴱ√SḶPḶ root. “*lick up”
References ✧ LT1A/Tanyasalpë; QL/84