Why is the ninth month called September?
masc. personal name, in medieval lore the name of one of Charlemagne's peers, friend of Roland, from French Olivier, from Middle Low German Alfihar, literally "elf-host, elf-army," from alf "elf" (see elf) + hari "host, army" (see harry (v.)). Cognate with Anglo-Saxon name Ælfhere. Form influenced in Old French by olivier "olive tree."