In early September 2011, the publicists at Collins Dictionaries produced a list of words which the dictionary’s editors considered to be obsolete and which were to be removed from the next edition of its dictionary. One of them is supererogate, to do more than is required of one, to go beyond the call of duty. The related noun, supererogation, is still used enough to be retained, however.
It comes from Latin superērogāre, from super-, beyond or above, plus ērogāre. The latter originally meant to pay out public money after asking the consent of the Roman people (it’s from rogāre, to ask). Superērogāre literally meant to pay more than was necessary. In its figurative sense it appeared first in the parable of the Good Samaritan in a Latin translation of the New Testament.
Supererogation has long had a special meaning within the Roman Catholic church for acts that are morally good but not required for salvation by God. Church doctrine holds that such good works make up a reserve fund of merit that can be drawn on by prayer in favour of sinners. In recent decades, supererogation has taken on another sense in philosophy, for a much-debated topic that refers to the nature of duty and to what extent moral actions can be optional.
More loosely, supererogation can refer to something that’s unnecessary or perhaps even undesirable:
For the rest, the staging is an act of supererogation, a distraction from the grandeur of Gluck’s opera.
The Times, 30 Oct. 2010.