flightless

adjective

flight·​less ˈflītlə̇s 

of a bird

: lacking the ability to fly

flightless downy young

especially : permanently unable to fly because of wing reduction accompanying evolutionary adaptation to certain specialized terrestrial habitats

—used chiefly of ratite birds

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Kids Definition

flightless

adjective

flight·​less

ˈflīt-ləs

: unable to fly

flightless birds