Qenya
qel-
verb. †to fail
qelet
noun. corpse
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 noun for “corpse” in The Etymologies written around 1937 derived from primitive ᴹ✶kwelett- under the root ᴹ√KWEL “fade (away)” (Ety/KWEL). It had a plural form qeletsi indicating a stem form of qelets-, but that is inconsistent with its attested primitive form; its plural may instead be a conceptual remnant of the Early Qenya sound change whereby [[eq|[ti] became [tsi]]] (PE12/23).
Conceptual Development: ᴱQ. qelet “corpse” appeared in the Qenya Lexicon of the 1910s under the early root ᴱ√QELE “perish, die, decay, fade”, but there its stem form was qelekt- (QL/76). ᴹQ. qelet “corpse” reappeared in the Declension of Nouns from the early 1930s, but there its stem form seems to be qelet- (PE21/33, 35). Its early 1930s nominative plural qeletsin also shows ti > tsi (PE21/35).
Neo-Quenya: For purposes of Neo-Quenya, I’d assume a stem form quelett- (and plural queletti) consistent with its primitive form. If the stem form was quelets-, then the uninflected form would be ✱✱queles, since final -ts became -s (PE19/104).