Early Primitive Elvish
usu
root. get out, escape
ʒuðu Reconstructed
root. *burn
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.
The root ᴱ√USU⁽⁾ appeared in the Qenya Lexicon of the 1910s with the gloss “get out, escape” and derivatives like ᴱQ. usu- “he escapes” and ᴱQ. uswe “issue, outlet, escape” (QL/98). In the contemporaneous Gnomish Lexicon it had derivatives like G. us(ta)- “leave, depart” and G. uthwen “way out, exit; escape” (GL/75), the latter hinting that the root form may have been a blending with ✱ᴱ√UÞU. I think it is worth positing a Neo-Eldarin root ᴺ√UTH to salvage these early words for “escape”.