Early Noldorin
gwardh
adjective. dead
gurdh-
verb. to die
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 for “die” in Early Noldorin Grammar of the 1920s with present form gwardh indicating vowel gradation (PE13/132), so that it was likely based on the early root ᴱ√GWṚÐṚ (QL/104) with a/u variations due to the different developments of long syllabic ṝ vs short ṛ.
Conceptual Development: The verb G. gor-“die” appeared in the Gnomish Lexicon of the 1910s related to gurthu “death” (GL/41, 43), thus also based on the early root ᴱ√GWṚÐṚ (QL/104).
Neo-Sindarin: S. gurth “death” survived in Tolkien’s later writings, so in theory the Gnomish verb gor- could be salvaged as a derivative of the later root √ÑGUR “die”. However, gor- already serves various functions in Sindarin, so I’d stick with the later verbs fir- and [N.] gwanna- for “to die”.