Sentence:  <WSD>Supererogation</WSD> is the technical term for the class of actions that go “beyond the call of duty.” Roughly speaking, supererogatory acts are morally good although not (strictly) required. ... Surprisingly, the history of <WSD>supererogation</WSD> in non-religious ethical theory is fairly recent, starting only in 1958 with J. O. Urmson's seminal article, “Saints and Heroes.” 
Meaning of the word marked with <WSD> tags:  An action that is neither morally forbidden nor required, but has moral value.