Source : Webster's Revised Unabridged Dictionary (1913)

Emu \E"mu\, n. [Cf. Pg. ema ostrich, F. ['e]mou, ['e]meu, emu.]
   (Zo["o]l.)
   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.

Source : WordNet®

emu
     n 1: any of various systems of units for measuring electricity
          and magnetism [syn: {electromagnetic unit}]
     2: large Australian flightless bird similar to the ostrich but
        smaller [syn: {Dromaius novaehollandiae}, {Emu
        novaehollandiae}]