What does "waistcoat" mean?

Waistcoat: (a) A short, sleeveless coat or garment for men, worn under the coat, extending no lower than the hips, and covering the waist; a vest. (b) A garment occasionally worn by women as a part of fashionable costume. Note: The waistcoat was a part of female attire as well as male . . . It was only when the waistcoat was worn without a gown or upper dress that it was considered the mark of a mad or profligate woman. Nares.