Middle Primitive Elvish
dag
root. dig
ndag
root. *slay
day
root. shadow
(n)dak
root. slay
dak
root. slay
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 rejected root in The Etymologies of the 1930s glossed “dig” (Ety/DAG), it may have been a transient replacement for √SAP.