Middle Primitive Elvish
gal
root. shine
gal
root. grow, thrive
galas
root. joy, be glad
gālæ
noun. light
ol
root. grow
kal
root. shine
kalat
noun. light
k’lā
noun. light
lot(h)
root. flower
There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
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.