1590s, from Medieval Latin supererogatorius, from supererogat-, stem of supererogare "pay or do additionally" (see supererogation).
Entries linking to supererogatory
supererogation n.
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 "above, over" (see super-) + erogare "pay out," from ex "out" (see ex-) + rogare "ask, request," apparently a figurative use of a PIE verb meaning literally "to stretch out (the hand)," from root *reg- "move in a straight line."