Middle Primitive Elvish
orot
root. height, mountain
pheleg
root. cave
rǭda
noun. cave
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 Etymologies of the 1930s glossed “height, mountain” given as an extension of ᴹ√ORO “up, rise, high”, with derivatives like ᴹQ. oron (oront-) “mountain” and N. orod “mountain” (Ety/ÓROT). The latter dates all the way back to G. orod “mountain” from the Gnomish Lexicon of the 1910s (GL/63), and continued to be used in later writings as S. orod as well (e.g. on LotR/469). The derivatives of the root on the Qenya side were more variable, sometimes given as Q. orto (PE17/64) or orot- (VT47/28) instead.