Qenya
tundo
noun. hill, mound, hill, mound [isolated]
tundo
noun. hole
ambo
noun. hill
Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
A noun in The Etymologies of the 1930s glossed “hill, mound” derived from the root ᴹ√TUN (Ety/TUN). Tolkien’s continued use of Q. Túna for the name of a hill in Valinor implies the ongoing validity of its root, so perhaps this word remained valid as well.
Neo-Quenya: For purposes of Neo-Quenya, I would assume that tundo refers mainly to a single isolated hill standing out from its surroundings, as opposed to Q. ambo for hills in general, but that’s speculation on my part.