Performed to an extent not enjoined, or not required, by duty or necessity; as, supererogatory services.

To act above or beyond the call of duty. A supererogatory act is morally good and goes beyond what is required by duty.

Literally, "above the call of duty." A supererogatory act is one that is morally good and that goes beyond what is required by duty. Some ethical theories, such as certain versions of utilitarianism, that demand that we always do the act that yields the most good have no room for supererogatory acts.

more than is needed, desired, or required; "trying to lose excess weight"; "found some extra change lying on the dresser"; "yet another book on heraldry might be thought redundant"; "skills made redundant by technological advance"; "sleeping in the spare room"; "supernumerary ornamentation"; "it was supererogatory of her to gloat"; "delete superfluous (or unnecessary) words"; "extra ribs as well as other supernumerary internal parts"; "surplus cheese distributed to the needy"