gnu: large African antelope having a head with horns like an ox and a long tufted tail
antelope: graceful Old World ruminant with long legs and horns directed upward and backward; includes gazelles; springboks; impalas; addax; gerenuks; blackbucks; dik-diks
fast of the firstborn: (Judaism) a minor fast day on Nissan 14 that is observed only by firstborn males; it is observed on the day before Passover