√OL root. “*grow”
This root seems to have served various purposes throughout Tolkien’s life. It first appeared as ᴱ√OLO¹ “tip”, unglossed ᴱ√OLO² with derivatives like ᴱQ. olde “very, much” and ᴱQ. olto- “increase, multiply”, as well as ᴱ√OLO³ whose derivatives had to do with dreams (QL/69). The second root ᴱ√OLO² may have had the sense “*increase, more”, which may have reemerged in the verb or primitive form ol- “grow” in a deleted entry from The Etymologies of the 1930s (EtyAC/GAL(AS)). The root ᴹ√OL “grow” was mentioned again in the Quenya Verbal System of the 1940s (PE22/103). In this document the Quenya verb Q. ol- generally had the gloss “become” (PE22/99-100, 113), even as a derivative of ᴹ√OL “grow” (PE22/103).
The sense “become” for the verb form was mentioned again in Common Eldarin: Verb Structure from the early 1950s (PE22/133-134). There are several more documents from around 1959 that have derivatives connected to the sense “growth”, such as Q. olmen “growth-year”, Q. olmië “growth” and Q. quantolië “maturity” (NM/84, 119-120). However, in The Shibboleth of Fëanor from the late 1960s Tolkien said: “OL as a simple stem seems not to have occurred in Eldarin, though it appears in certain ‘extended’ stems, such as olos/r ‘dream’, olob ‘branch’ (PM/341)”. This lack of ancient meaning was despite the fact that OL was an element in the ancient name Q. Olwë.
Neo-Eldarin: For purposes of Neo-Eldarin, I think it is best to assume √OL meant “grow, *become”, which could easily contribute to the extended forms √OLOS “dream” and √OLOB “branch”. As a root, I think it primarily refers to the growth of people or animals, as opposed to √GAL used for the growth of plants. I think √OL can also be used for more abstract senses of “growth”, include “grow into” and hence “become”.
References ✧ PM/340-341
ᴹ√OL root. “grow”
References ✧ EtyAC/GAL(AS); PE22/103
ᴱ√OLO² root. “*increase, more”
Reference ✧ QL/69