The name Casey is a Celtic baby name. In Celtic the meaning of the name Casey is: Brave. Gaelic Meaning: The name Casey is a Gaelic baby name. In Gaelic the meaning of the name Casey is: Brave.American Meaning: The name Casey is an American baby name. In American the meaning of the name Casey is: Brave.English Meaning: The name Casey is an English baby name. In English the meaning of the name Casey is: From a polish word meaning 'Proclamation of peace.' A, Cassandra, or Catherine.Popularized as a boy's name by the American folk song 'Casey Jones'.he name Casey is an English baby name. In English the meaning of the name Casey is: From a polish word meaning 'Proclamation of peace.' A, Cassandra, or Catherine. Popularized as a boy's name by the American folk song 'Casey Jones'.