qualm

Etymology

Perhaps from Middle English qualm, cwalm (“death, sickness, plague”), itself from Old English cwealm (West Saxon: "death, disaster, plague"), ūtcualm (Anglian: "utter destruction"), from Proto-West Germanic *kwalm (“killing, death, destruction”), from Proto-Indo-European *gʷelH- (“to stick, pierce; pain, injury, death”), which also gave quell. Although this sense development is plausible, it runs into the problem that no intermediate senses are attested before "pang of apprehension, etc." appears in the 16th century. An alternative traces it to Dutch kwalm or German Qualm (“steam, vapor, mist”), earlier “daze, stupefaction”, from the root of German quellen (“to stream, well up”). The sense “feeling of faintness” dates from 1530; “uneasiness, doubt” from 1553; and “scruple of conscience” from 1649.