Middle Primitive Elvish
peg
root. (?outer) mouth
mit
root. small
mitra
adjective. small
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 glossed “small” with various Quenya and Noldorin derivatives of similar meaning (Ety/MIT).