Short form of Antonia, Catharina and Cato 2. The -s might possibly indicate that the name originated from a diminutive of these names, such as Teunisje for Antonia (variants include Tonisje, Toonisje and Toonsje) and the extremely rare Catoosje for Cato (see Catootje, which is much more common).
indicate the level to which a name has been verified.