A root in The Etymologies of the 1930s glossed “joy, be glad” that is an extension of ᴹ√GALA “thrive” (Ety/GALAS). Its two most notable derivatives were ᴹQ. alasse and N. glass “joy”. The appearance of Q. alassë “happiness” in the so-called “Merin Sentence” (MS), probably written after the publication of The Lord of the Rings, indicates that this root may have remained valid.
Middle Primitive Elvish
galā-
verb. to grow
gal
root. grow, thrive
galad
root. tree
galas
root. joy, be glad
galadā
noun. tree
golā-
verb. to grow
ol
root. grow
The basis for Elvish “tree” words, this root first appeared in The Etymologies of the 1930s as an extension of ᴹ√GALA “thrive” (Ety/GALAD). This replaced the earliest derivation of “tree” from the Qenya Lexicon of the 1910s, where the Qenya word for “tree” ᴱQ. alda was derived from ᴱ√ALA “spread” (QL/29). In The Etymologies, the Quenya form of this word remained the same, but the 1910s Gnomish words G. âl “wood” and †alwen “tree” (GL/19) became the 1930s Noldorin word N. galadh “tree” (Ety/GALA). Quenya and Sindarin retained these words for “tree” thereafter, and while Tolkien did not mention the root √GALAD again, his continued use of primitive ✶galadā “tree” (Let/426; PE17/153; PE21/74; UT/266) made it clear this root remained valid.