1) Contrition 2) French word used in English 3) Regret 4) Remorse 5) Ruefulness 6) Self-reproach 7) Sorrow 1) Doubts 2) Misgiving 3) Penance 4) Penitence 5) Penitential 6) Qualm 7) Regret 8) Remorse 9) Repentance 10) Rue 
regret; remorse
• (n.) A picking of heart; poignant grief proceeding from a sense of guilt or consciousness of causing pain; the sting of conscience. • (n.) A pricking; stimulation.
[Noun] Doing something without compunction means that you feel no guilt or shame about doing it. 
Com·punc'tion noun [ Old French compunction , French componction , Latin compunctio , from compungere , compunctum , to prick; com- + pungere to prick, sting. See Pungent .] 1. A pricking; stimulation. [ Obsolete] « That acid a...
feeling of regret for one's action 
[n] - a feeling of deep regret (usually for some misdeed)
compunction 1. A strong feeling of uneasiness or anxiety of the conscience caused by regret or guilt for doing wrong or causing pain; contrition; remorse; penitence. 2. Any uneasiness or hesitation about the rightness of an action. 3. A sting of conscience or a pang of doubt aroused by wrongdoing or the prospect of wrongdoing.
[Wuthering Heights] a sharp feeling of uneasiness brought on by a sense of guilt.
remorse noun a feeling of deep regret (usually for some misdeed)
a feeling of uneasiness or anxiety of the conscience caused by regret for doing wrong or causing pain; contrition; remorse. · any uneasiness or hesitation about the rightness of an action.
a feeling of deep regret, usually for some misdeed