Early Primitive Elvish
tiri
root. watch; guard; observe
tiři
root. ‽stick up
tiði Reconstructed
root. ‽stick up
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 given as ᴱ√TIŘI [TIÐI] “stick up” in the Qenya Lexicon of the 1910s (though Tolkien marked the gloss with “?”), with derivatives like ᴱQ. tinda “spike”, ᴱQ. tirin “tower”, and ᴱQ. tirion “a mighty tower, a city on a hill” (QL/93). In later writings, the city name Q. Tirion “Great Watch Tower” (RGEO/65) or “Watchful City” (MR/176) was almost certainly derived from the root √TIR “watch”.