The earliest Elvish words for “eight” were ᴱQ. {ungo >>} umna and G. {ung >>} uvin in the Gnomish Lexicon of the 1910s (GL/75), but in the Early Qenya Grammar of the 1920s it became ᴱQ. {telte >>} tolto (PE14/49). In The Etymologies of the 1930s Tolkien gave the root ᴹ√TOL-OTH/OT “eight” as the basis for ᴹQ. tolto and N. toloth of the same meaning (Ety/TOL¹-OTH/OT); in this document it was distinct from ᴹ√TOL which was the basis for “island” words.
In documents on Elvish numbers from the late 1960s, Tolkien vacillated between √TOLOTH (VT42/30 note #52), √TOLOT (VT42/24; VT47/31) and √TOLOD (VT47/11) for the form of this root, but in the more polished versions of these documents he seems to have settled on √TOLOD > Q. toldo, S. toloð (VT48/6). In this last iteration, Tolkien connected the root √TOLOD to the root √TOL “stick up” due to the prominence of the middle fingers (3 and 8) in counting (VT47/11); see the entry on √TOL for discussion.
This was the root for islands and other things that “stick up” for much of Tolkien’s life. This root appeared as unglossed ᴱ√TOLO in the Qenya Lexicon of the 1910s with derivatives like ᴱQ. tol “an island”, ᴱQ. tolda “hill with a flat top; town on a hill”, and ᴱQ. tolmen “boss (of shield), isolated round hill” (QL/94). The derivative G. tol “an isle (with high steep coasts)” appeared in the contemporaneous Gnomish Lexicon as well (GL/71). The root appeared as ᴹ√TOL in The Etymologies of the 1930s with derivatives ᴹQ. tol/N. toll “island” (Ety/TOL²); the alternate root ᴹ√TOL was the basis for words for “eight” in this document. The root was mentioned several times in writings on Eldarin Hands, Fingers and Numerals from the late 1960s, with glosses like “stand up (out and above neighboring things)” (VT47/10) or “stick up or out” (VT47/28), and Tolkien said it:
> mostly applied to things that were, relatively to those that they were contrasted with, also larger and thicker: e.g. mountain-tops, very tall trees, or a tall strong man (VT47/10).
In this last respected it was the basis for various words for “thumb” and “big toe”, and could be contrasted with √TIL used for the tips of smaller things, including the smaller fingers and toes. √TOL also had extended form √TOLOB with derivative ✶tolbā “a protuberance, esp. one designed for a purpose: a knob or rounded tool-handle” (VT47/11), and in these 1960s documents (unlike in the 1930s) it was the basis for the root √TOLOD “eight” due to the prominence of the middle finger (finger 3 and 8) in counting (VT47/11).