The Collaborative International Dictionary of English v.0.48:

Devoir \De*voir"\, n. [F., fr. L. debere to owe. See Due.]
   Duty; service owed; hence, due act of civility or respect; --
   now usually in the plural; as, they paid their devoirs to the
   ladies. "Do now your devoid, young knights!" --Chaucer.
   [1913 Webster]

WordNet (r) 3.0 (2006):

devoir
    n 1: formal expression of respect

Bouvier's Law Dictionary, Revised 6th Ed (1856):

DEVOIR. Duty. It is used in the statute of 2 Ric. II., c. 3, in the sense of
duties or customs.