Why is the ninth month called September?
1540s, "mounted trooper," from French contraction (14c.) of gens d'armes "men at arms," later applied to military police (1796 in English). Gens is plural of gent "nation, people," from Latin gentem (nominative gens) "race, nation, people" (see genus). Related: Gendarmerie. French also had gens de (la) robe "lawyers," sometimes borrowed in English.