con·science 
/ˈkɑ:nʃəns/ noun
plural con·scienc·es /ˈkɑ:nʃəns/ noun 1 : the part of the mind that makes you aware of your actions as being either morally right or wrong [count] — usually singular ▪ You should decide what to do according to your own conscience. ▪ Her conscience was bothering her, so she finally told the truth. ▪ He doesn't seem to have a conscience. [=doesn't seem to know or care about what is morally right] ▪ I cannot do anything that is/goes against my conscience. [=that I believe is morally wrong] ▪ After searching my conscience, I realized that I could not accept their offer. ▪ At least now I can face him with a clear conscience. [=without guilt] ▪ She had a guilty/troubled conscience. [=she had a feeling of guilt about something she had done] ▪ I urged the senator to vote his conscience [=vote as he felt he should], even if it was at odds with the party line. [noncount] ▪ The issue is a matter of (individual) conscience. [=something that people must decide about according to what they believe is morally right] ▪ I can't work for a company that has no social conscience. [=a company that does not care about important social issues] — see also prisoner of conscience 2 [noncount] : a feeling that something you have done is morally wrong
▪ She felt a pang/prick of conscience [=guilt] about not inviting him. ▪ The thief must have had an attack of conscience, because he returned the wallet with nothing missing from it.
▪ She felt a pang/prick of conscience [=guilt] about not inviting him. ▪ The thief must have had an attack of conscience, because he returned the wallet with nothing missing from it.
in (all/good) conscience
formal ◊If you cannot do something in (all/good) conscience, you cannot do it because you think that it is morally wrong.
▪ I cannot in good conscience allow this situation to continue. ▪ She could not in all conscience remain silent.
▪ I cannot in good conscience allow this situation to continue. ▪ She could not in all conscience remain silent.
on your conscience
◊If something is on your conscience, it makes you feel guilty.
▪ I have to tell you the truth, because I don't want this on my conscience any longer.
▪ I have to tell you the truth, because I don't want this on my conscience any longer.
