Full Definition of SWASTIKA. 1. : a symbol or ornament in the form of a Greek cross with the ends of the arms extended at right angles all in the same rotary direction. 2.: a swastika used as a symbol of anti-Semitism or of Nazism.See swastika defined for English-language learners.. : a symbol or ornament in the form of a Greek cross with the ends of the arms extended at right angles all in the same rotary direction. 2. : a swastika used as a symbol of anti-Semitism or of Nazism.