Early Quenya
sisi-
verb. to scorch, singe, fry
hisilóme
place name. Shadowy Twilights, Misty-gloom
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 verb in the Qenya Lexicon of the 1910s appearing as ᴱQ. sisi- “scorch, singe, fry” derived from the early root ᴱ√SISI “singe, etc.” (QL/84). The root’s likely Gnomish derivatives such as G. thista- “dry up” (GL/73) indicate the root form is probably ✱ᴱ√ÞISI.
Neo-Quenya: I think this word is worth salvaging as Neo-Quenya ᴺQ. sis-, though it would need to be derived from a Neo-Root ᴺ√THITH to retain this same form.