Real Dictionary

ostrich
countable noun: An ostrich is a very large African bird that cannot fly.

ostrich in American English
a swift-running bird (Struthio camelus) of Africa and SW Asia, the only member of its order (Struthioniformes): it is the largest and most powerful of living birds, and has a long neck, very long legs with two toes on each foot, and small, useless wings:
noun: a large, two-toed, swift-footed flightless bird, Struthio camelus, indigenous to Africa and Arabia, domesticated for its plumage: the largest of living birds

ostrich in British English
noun: a fast-running flightless African bird, Struthio camelus, that is the largest living bird, with stout two-toed feet and dark feathers, except on the naked head, neck, and legs: order Struthioniformes