According to a legend, the town initially was known as Tusk; however, after a flood that destroyed half of the city, it was renamed as Pułtusk (Pół- or puł- being a Polish prefix for a half).
Conform legendei, localitatea s-a numit inițial Tusk, dar în urma unui potop care a distrus jumătate din oraș, acesta a fost redenumit Puștusk ("Pół" sau "puł" este un prefix polonez pentru "jumătate").