From the ArcaMax Publishing, Vocabulary Newsletter:
http://www.arcamax.com/news/vocabulary/s-367517-882706
compunction \kuhm-PUHNK-shuhn\ (noun) - 1 : Anxiety or deep unease
proceeding from a sense of guilt or consciousness of causing pain. 2 :
A sting of conscience or a twinge of uneasiness; a qualm; a scruple.
"However, he died intestate: I was his heir-at-law, and I felt a
certain compunction in taking his money -- he would so have disliked
my having it." -- Patrick O'Brian, 'Testimonies'
Compunction derives from Late Latin compunctio, compunction-, "sting
or pricking of conscience," from the past participle of compungere,
"to prick severely," from com-, intensive prefix + pungere, "to
prick."