A set of related adjectives in the Qenya Lexicon of the 1910s: ᴱQ. qalma “deadly”, qalmea “deathly” and (archaic) †qalūmea equivalent to qalma, all based on ᴱQ. qalme or †qalume “death” (QL/76).
Neo-Quenya: Since [ᴹQ.] qualme “death” continued to appear in Tolkien’s later writings (Ety/KWAL), I’d adapt these adjectives as ᴺQ. qualmëa “deadly, deathly”, applied mainly to things apt to cause death.
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).