- ethics, especially that branch dealing with duty, moral obligation, and right action.
- the branch of ethics dealing with duty, moral obligation, and moral commitment
science of moral duty, 1826, from Greek deont-, comb. form of deon “that which is binding, duty,” neuter present participle of dei “is binding;” + -logia “discourse” (see -logy). Said to have been coined by Bentham. Related: Deontological.