Source : Webster's Revised Unabridged Dictionary (1913)

Qualm \Qualm\, n. [AS. cwealm death, slaughter, pestilence, akin
   to OS. & OHG. qualm. See {Quail} to cower.]
   1. Sickness; disease; pestilence; death. [Obs.]

            thousand slain and not of qualm ystorve [dead].
                                                  --Chaucer.

   2. A sudden attack of illness, faintness, or pain; an agony.
      `` Qualms of heartsick agony.'' --Milton.

   3. Especially, a sudden sensation of nausea.

            For who, without a qualm, hath ever looked On holy
            garbage, though by Homer cooked?      --Roscommon.

   4. A prick or scruple of conscience; uneasiness of
      conscience; compunction. --Dryden.

Source : WordNet®

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