This root was connected to Elvish words for “wisdom” for much of Tolkien’s life, the most notable derivative being Q. Noldo. In the Qenya Lexicon of the 1910s it was given as ᴱ√ŇOL(O) “know”, where the Ň almost certainly represented velar nasal Ŋ (QL/67). It was originally given simply as ŇOLDO “goblin, gnome” along with a derivative ᴱQ. noldare “mole”, but the “goblin” entries were removed and “mole” was transferred to ᴱ√NDOLO “delve”, so the connection of this root to knowledge was a very early decision. In the contemporaneous Gnomish Lexicon primitives forms were likewise given as ᴱ✶ŋolđō > G. golda “gnome, wise one” (GL/41).
In The Etymologies of the 1930s the root appeared as ᴹ√ÑGOL “wise, wisdom, be wise” along with an extended form ᴹ√ÑGOLOD serving as the basis for ᴹQ. Noldo/N. Golodh (Ety/ÑGOL; ÑGOLOD). This root and its extended form were mentioned regularly in Tolkien’s later writings, with glosses like “knowledge” (PE17/79) and “knowledge, wisdom, lore” (WJ/383), and in one place Tolkien clarified that it was “deep knowledge not ‘occult’ in modern sense, but applied to the deeper knowledge of the ‘wise’ or skilled persons, not kept secret ... but [also] not attainable by all” (PE17/79).