The Collaborative International Dictionary of English v.0.48:

Emulator \Em"u*la`tor\, n. [L. aemulator.]
   One who emulates, or strives to equal or surpass.
   [1913 Webster]

         As Virgil rivaled Homer, Milton was the emulator of
         both.                                    --Bp.
                                                  Warburton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

emulator
    n 1: someone who copies the words or behavior of another [syn:
         copycat, imitator, emulator, ape, aper]

The Free On-line Dictionary of Computing (30 December 2018):

emulator

   Hardware or software that performs emulation.

   (1995-05-12)