Early Quenya
qalme
noun. death, agony
qalume Archaic
noun. death
qalme-tári
feminine name. Mistress of Death
maldor
noun. agony
urdu
noun. death
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 name of Nienna as the Mistress of Death in the earliest Lost Tales (LT1/66), a combination of qalme “death” and tári “queen” as suggested by Christopher Tolkien (LT1A/Qalmë-Tári).