A noun in The Etymologies of the 1930s glossed “sickness” under the root ᴹ√KWAM (Ety/KWAM). ᴱQ. qáme also appeared in the Qenya Lexicon of the 1910s with the glosses “sickness, nausea” under the early root ᴱ√QAMA (QL/76).
Neo-Quenya: For purposes of Neo-Quenya, I would assume this noun applies mainly to stomach illnesses and nausea, as opposed to general sickness which would be [ᴺQ.] hlívë.
A noun appearing as ᴹQ. líve “sickness” in The Etymologies of the 1930s derived from primitive ᴹ✶slīwē under the root ᴹ√SLIW “sickly” (Ety/SLIW). The ancient initial sl became voiceless hl, which was then voiced to l as was generally the case in The Etymologies. The root had a deleted variant ᴹ√LIW “be sickly, ill”, where líve appeared with the gloss “disease” (EtyAC/LIW).
Neo-Quenya: In Tolkien’s later writing, he usually retained hl- in spelling if not pronunciation; see the entry on how initial voiceless nasals and liquids were voiced for discussion. As such, most Neo-Quenya writers adapt this word as ᴺQ. hlívë. Given the gloss “disease” for its deleted form, I would further assume hlívë specifically refers to sickness by disease.
Conceptual Development: The Qenya Lexicon of the 1910s had the word ᴱQ. leume “sickness” under the similar but earlier root ᴱ√LEẆE (QL/53).