devoir
Concise Oxford English Dictionary © 2008 Oxford University Press:
devoir /dəˈvwɑː/
▶noun archaic a person's duty.
– phrases
pay one's devoirs pay one's respects formally.
pay one's devoirs pay one's respects formally.
– origin ME: from OFr. deveir, from L. debere ‘owe’, influenced by Fr. devoir.
'devoir' also found in these Oxford entries:

