The Collaborative International Dictionary of English v.0.48:

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.]
   [1913 Webster]

   Note: The name is sometimes erroneously applied, by the
         Brazilians, to the rhea, or South American ostrich.
         [1913 Webster]

   Emu wren. See in the Vocabulary.
      [1913 Webster]

WordNet (r) 3.0 (2006):

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

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

EMU
       EAP Method Update (EAP)