The Collaborative International Dictionary of English v.0.48:

Qualm \Qualm\, n. [AS. cwealm death, slaughter, pestilence, akin
   to OS. & OHG. qualm. See Quail to cower.]
   1. Sickness; disease; pestilence; death. [Obs.]
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            thousand slain and not of qualm ystorve [dead].
                                                  --Chaucer.
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   2. A sudden attack of illness, faintness, or pain; an agony.
      " Qualms of heartsick agony." --Milton.
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   3. Especially, a sudden sensation of nausea.
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            For who, without a qualm, hath ever looked
            On holy garbage, though by Homer cooked?
                                                  --Roscommon.
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   4. A prick or scruple of conscience; uneasiness of
      conscience; compunction. --Dryden.
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WordNet (r) 3.0 (2006):

qualm
    n 1: uneasiness about the fitness of an action [syn: scruple,
         qualm, misgiving]
    2: a mild state of nausea [syn: queasiness, squeamishness,
       qualm]