the inner sense of what is right or wrong in one's conduct or motives, impelling one toward right action

to follow the dictates of conscience.

the complex of ethical and moral principles that controls or inhibits the actions or thoughts of an individual.

an inhibiting sense of what is prudent

I'd eat another piece of pie but my conscience would bother me.

conscientiousness.

Obsolete . consciousness; self-knowledge.

Obsolete . strict and reverential observance. ?

have something on one's conscience, to feel guilty about something

as an act that one considers wrong

She behaves as if she had something on her conscience.

in all conscience

in all reason and fairness.

certainly; assuredly. Also, in conscience.

adjective

ruthless , unconscionable , unethical , unprincipled