Why is the ninth month called September?
"baton-twirler," 1941, short for drum-majorette (1938), fem. of drum-major (1590s).
The perfect majorette is a pert, shapely, smiling extrovert, who loves big, noisy crowds and knows how to make those crowds love her. ["Life" magazine, Oct. 10, 1938](The article notes that the activity "has been going on for about six years now").