Early Primitive Elvish
pili
root. rob
pili
root. *feather; arrow
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 Qenya Lexicon of the 1910s glossed “rob”, with derivatives like ᴱQ. pili- “steal”, ᴱQ. pilu “thief, robber” and ᴱQ. pilwe “robbery, theft” (QL/74). There are no signs of this root in Tolkien’s later writing, but I think it is worth retaining as the Neo-Eldarin basis for “theft” words. A possible later replacement might be the root √RAPH “seize, grab” from the Outline of Phonology (OP2) from the early 1950s which had the derivative Q. arpo “seizer, thief” (PE19/89).