Definition that contains lightless
- penguin short-legged flightless birds of cold southern especially Antarctic regions having webbed feet and wings modified as flippers
- rhea smaller of two tall fast-running flightless birds similar to ostriches but three-toed; found from Peru to Strait of Magellan
- rhea larger of two tall fast-running flightless birds similar to ostriches but three-toed; found from Brazil to Patagonia
- ostrich fast-running African flightless bird with two-toed feet; largest living bird
- nandu smaller of two tall fast-running flightless birds similar to ostriches but three-toed; found from Peru to Strait of Magellan
- kiwi nocturnal flightless bird of New Zealand having a long neck and stout legs; only surviving representative of the order Apterygiformes
- dodo extinct heavy flightless bird of Mauritius related to pigeons
- solitaire extinct flightless bird related to the dodo
- moa extinct flightless bird of New Zealand
- emu large Australian flightless bird similar to the ostrich but smaller