Flightless creature (3)
(Other definitions for emu that I've seen before include "Australian running bird." , "that doesn't get off the ground" , "Large Australian flightless bird" , "Physics unit" , "Native Australian bird" .)
(Other definitions for ostrich that I've seen before include "Largest living bird" , "Emu-like bird" , "Runner" , "Fast-running African flightless bird" , "Torch is raised for big bird" .)