Definition of "devoir"

[…] he imprint not so much in his schollers mind […] where Marcellus died, as because he was unworthy of his devoire he died there […].

1603, Michel de Montaigne, translated by John Florio, The Essayes […], book I, London: […] Val[entine] Simmes for Edward Blount […], page 149

I should have long ere this paid my devoirs to the inhabitants of Raymond Castle.

1787, “A female” [pseudonym; Winifred Marshall Gales], The History of Lady Emma Melcombe, and Her Family. By a Female. In Three Volumes, volume III, London: Printed for G. G. J. and J. Robinson, page 155

[M]y eyes were oft times [on the] charmante maitresse de la maison, who glided among her guests in her flowing Spanish mantilla, and train of the clearest blonde, doing her devoirs with winning kindness, and showing how much benevolence of manner adds to beauty.

1836 July, “London Fashionable Chit-Chat”, in The Lady's Magazine and Museum of the Belles-lettres, Fine Arts, Music, Drama, Fashions, &c. (Improved Series. Enlarged.), volume IX, London: Dobbs & Co., Hemlock Court, Carey Street, Lincolns Inn (Formerly at 112, Fetter Lane), page 73

A young man who arrives at Florence late in the evening, and, instead of going prosaically to bed, or hanging over the travellers' book at his hotel, walks forth without loss of time to pay his devoirs to the Beautiful, is a young man after my own heart!

1873 March, H[enry] James Jr., “The Madonna of the Future”, in The Atlantic Monthly: A Magazine of Literature, Science, Art, and Politics, volume XXXI, number CLXXXV, Boston, Mass.: James R. Osgood and Company, late Ticknor & Fields, and Fields, Osgood & Co., page 277

Then quoth the portress to the mistress of the house, "O my lady, arise and go to thy place that I in turn may do my devoir."

1885, Richard F[rancis] Burton, The Book of the Thousand Nights and a Night, Benares [false, actually Stoke Newington, London]: Kamashastra Society

That is the little bit of essential information which enables us to complete our devoir – without it we are just ordinary people, dispossessed, taken unawares: the original sin!

1983, Lawrence Durrell, Sebastian, or Ruling Passions (The Avignon Quintet; 4), London; Boston, Mass.: Faber & Faber, ISBN 978-0-571-13111-2; republished in The Avignon Quintet, London: Faber & Faber, 2004, ISBN 978-0-571-22555-2, page 1057