Early Quenya
ossa
noun. wall and moat
hosse
noun. wall and moat
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 word for “wall & moat” in the Qenya Lexicon of the 1910s under the early root ᴱ√OSO (QL/71). In the contemporaneous Poetic and Mythological Words of Eldarissa it was hosse “wall & moat” instead (PME/71).