The Collaborative International Dictionary of English v.0.48:
Emu \E"mu\, n. [Cf. Pg. ema ostrich, F. ['e]mou, ['e]meu, emu.]
A large Australian bird, of two species (Dromaius
Nov[ae]-Hollandi[ae] and D. irroratus), related to the
cassowary and the ostrich. The emu runs swiftly, but is
unable to fly. [Written also emeu and emew.]
Note: The name is sometimes erroneously applied, by the
Brazilians, to the rhea, or South American ostrich.
Emu wren. See in the Vocabulary.