ᴺS. [ᴱN.] ^nîw n. “bee” (Category: Bee)
A word appearing as ᴱN. nui “a bee” in Early Noldorin Word-lists of the 1920s (PE13/151). Its exact etymology is unclear.
Conceptual Development: In the Gnomish Lexicon of the 1910s, Tolkien gave several variant forms for “bee”: G. nio, nios or nion (the last of these was rejected), and feminine G. niwin; Tolkien also considered but rejected nios as a feminine form (GL/60). The base forms nio and nios were derived from primitive ᴱ✶nēgu and ᴱ✶nēgis respectively, most likely from a variant of the early root ᴱ√NEHE which was the basis for “honey” and “bee” words in the contemporaneous Qenya Lexicon (QL/65). Early Noldorin Word-lists of the 1920s had ᴱN. nui as mentioned above, as well as an unglossed word ᴱN. niw which might be a variant (PE13/151).
Neo-Sindarin: In Tolkien’s later writings, the root √NEG “ooze, drip” was still connected to “honey” (PE19/91). Thus I think primitive *nēgū might still be viable as an ancient word for “bee”, which would most likely become ᴺS. nîw in Neo-Sindarin after ancient ē became ī. Compare S. lhaw “ears” from ancient dual *slasū for an example of how the final u would become diphthongal after the loss of an intervening weakened consonant, thus: *nēgū > *nīɣu > nīu̯, spelled nîw.
References ✧ PE13/151
References ✧ GL/60; LT1A/Nielluin