Maure
Traiter quelqu’un de Turc à Maure = To treat a person brutally.
[As the Turks treated the Moors when they conquered the north of Africa. See Molière, Précieuses Ridicules, 10.]
*À laver la tête d’un Maure (or, d’un âne, or, d’un nègre) on y perd sa lessive = To endeavour to teach a fool is a waste of time.
Mèche
Il a éventé (or, vendu) la mèche = He has let the cat out of the bag; He has blown the gaff.
Il n’y a pas mèche (pop.) = “It’s no go”; There is no doing it.
Médaille
C’est le revers de la médaille = That is the dark side of the picture.
Médard