This root has a long history in Tolkien’s development of the Elvish languages, but its exact meaning is hard to determine because Tolkien rarely translated the root itself. The earliest appearance of the root was as unglossed ᴱ√LIPI from the Qenya Lexicon of the 1910s where Tolkien indicated it might be a dialectical variant of ᴱ√LIQI “flow, water; clear, transparent”; it had derivatives like ᴱQ. lipte- “to drip”, ᴱQ. litl “a tiny drop”, and ᴱQ. limpe “elfwine” (QL/54). It also had derivatives in the contemporaneous Gnomish Lexicon such as G. lib “drop, gout”, G. lib- “to drip”, G. limp(elis) “the drink of the fairies” (GL/54). I think the most likely meaning of this early root was “✱drip, drop”.
In The Etymologies of the 1930s, the root for “drip” was ᴹ√LIB. ᴹ√LIP appeared, but it was unglossed and its only derivative was ᴹQ. limpe “wine” (Ety/LIB¹, LIP). Thus it seems Tolkien split up the root from the 1910s, though exactly how isn’t clear. The last known mention of this root is as √LIP “oil” (without any derivatives) in a currently unpublished set of notes from 1968 (VT44/15). Wynne, Smith, and Hostetter suggested this might be connect to a (rejected) name for Christ: Q. Elpino, perhaps meaning “✱anointed” (VT44/15). It is unclear whether this √LIP “oil” was connect to its earlier iterations from which limpe “wine” was derived, or if it is was a reemergence of a different root such as ᴱ√ILI “shine oily” as suggested by Wynne, Smith, and Hostetter (VT44/20 note #7).
A root meaning “all” in Tolkien’s writings from the 1930s through 1960s (VT48/25) with derivatives in both Quenya and Sindarin, the most notable being Q. Ilúvatar “All-father” (MR/39). Its earliest precursor is the root ᴱ√ILU “ether, the slender airs among the stars” from the Qenya Lexicon of the 1910s, whose derivatives include various sky-words as well as ᴱQ. Ilúvatar, since in this early period the name meant “Heavenly Father” (QL/42). The meaning of the root shifted to ᴹ√IL “all” in The Etymologies of the 1930s (Ety/IL), and it retained this sense thereafter.