An effort above and beyond the call of duty

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1520s, "performance of more than duty requires," in Catholic theology, from Late Latin supererogationem (nominative supererogatio ) "a payment in addition," noun of action from past participle stem of supererogare "pay or do additionally," from Latin super ...

Wiktionary Word definitions in Wiktionary
n. Doing more than is required.

WordNet Word definitions in WordNet
n. an effort above and beyond the call of duty

Wikipedia Word definitions in Wikipedia
Supererogation ( Late Latin : supererogatio "payment beyond what is due or asked", from super "beyond" and erogare "to pay out, expend" [from ex "out" and rogare "to ask"]) is the performance of more than is asked for; the action of doing more than duty ...

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Supererogation \Su`per*er`o*ga"tion\, n. [L. supererogatio a payment in addition.] The act of supererogating; performance of more than duty or necessity requires. Works of supererogation (R. C. Ch.), those good deeds believed to have been performed by saints, ...