A Qualm

1. A feeling of apprehension, doubt, fear etc. [from 16th c.]
2. A sudden sickly feeling; queasiness. [from 16th c.]
3. A prick of the conscience; a moral scruple, a pang of guilt. (Now often in negative constructions.) [from 17th c.]
4. (archaic, UK dialectal) Mortality; plague; pestilence.
5. (archaic, UK dialectal) A calamity or disaster.

Synonyms

• compunction
• misgiving
• scruple
• unease/uneasiness
• apprehension