The Collaborative International Dictionary of English v.0.48:
copycat \cop"y*cat`\, copy cat \cop"y cat`\n. someone who copies the words or behavior of another. Syn: imitator, ape, aper. [WordNet 1.5]WordNet (r) 3.0 (2006):
copycat n 1: someone who copies the words or behavior of another [syn: copycat, imitator, emulator, ape, aper]