scruple

Short definition from Wiktionary

Noun

1. 1
   Hesitation to act from the difficulty of determining what is right or expedient; doubt, hesitation or unwillingness due to motives of conscience; moral qualm.
2. 2
   A weight of ¹⁄₂₈₈ of a pound, that is, twenty grains or one third of a dram, about 1.3 grams (symbol: ℈).
3. 3
   A Hebrew unit of time equal to ¹⁄₁₀₈₀ hour.
4. 4
   A very small quantity; a particle.
5. 5
   A doubt or uncertainty concerning a matter of fact; intellectual perplexity.

Verb

1. 1
   To hesitate or be reluctant to act due to considerations of conscience or expedience.
2. 2
   To excite scruples in; to cause to scruple.
3. 3
   To regard with suspicion; to question.
4. 4
   To question the truth of (a fact, etc.); to doubt; to hesitate to believe, to question.