1. An uneasy feeling about the propriety or rightness of a course of action: "an ignorant ruffianly gaucho, who ... would ... fight, steal, and do other naughty things without a qualm" (W.H. Hudson).

2. A sudden disturbing feeling: "I heard with a qualm of terror the faint, remorseless sound of a telephone ringing somewhere down in the depths of the house" (John Banville).

3. A sudden feeling of sickness, faintness, or nausea.