Middle Primitive Elvish
pantā
adjective. open
yenpanta
adjective. aged, long-lived
kwantā Reconstructed
adjective. full
ed(er)
root. open
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 deleted root in The Etymologies of the 1930s with the gloss “open” and the forms √ED and extended √EDÉR, but it had no derivatives (EtyAC/ED).