qualm
definition
a feeling of unease or doubt about whether you are doing the right thing
example
She had a qualm about lying to her friend, fearing it might damage their relationship.
synonyms
misgivinguncertaintydoubt
word origin — The word 'qualm' comes from the Old Norse word 'kvalm', meaning 'nausea' or 'anguish', which is related to the Old English 'cwealm', meaning 'death' or 'destruction'.