Merriam-Webster Collegiate Dictionary - qualm

 noun  Etymology: origin unknown  Date: circa 1530  1. a sudden attack of illness, faintness, or nausea  2. a sudden access of usually disturbing emotion (as doubt or fear)  3. a feeling of uneasiness about a point especially of conscience or propriety  • ~y adjective Synonyms:  ~, scruple, compunction, demur mean a misgiving about what one is doing or going to do. ~ implies an uneasy fear that one is not following one's conscience or better judgment no ~s about plagiarizing. scruple implies doubt of the rightness of an act on grounds of principle no scruples against buying stolen goods. compunction implies a spontaneous feeling of responsibility or compassion for a potential victim had compunctions about lying. demur implies hesitation caused by objection to an outside suggestion or influence accepted her decision without demur.