•An inner sense which distinguishes what is right from what is wrong, functioning as a guide (like the needle of a compass) for morally appropriate behavior.
•A person, belief system, etc. serving as a guide for morally appropriate behavior.
•The full range of virtues, vices, or actions which may affect others and which are available as choices (like the directions on the face of a compass) to a person, to a group, or to people in general.
From moral (“of or relating to principles of right and wrong in behaviour; conforming to a standard of right behaviour”) + compass (“device used to determine the cardinal directions”), from the fact that a compass indicates various directions on its face (sense 3), and enables its user to find the correct direction to go in (sense 1).