The Collaborative International Dictionary of English v.0.48:

Impersonation \Im*per`son*a"tion\, Impersonification
\Im`per*son`i*fi*ca"tion\, n.
   The act of impersonating; personification; investment with
   personality; representation in a personal form.
   [1913 Webster]

WordNet (r) 3.0 (2006):

impersonation
    n 1: a representation of a person that is exaggerated for comic
         effect [syn: caricature, imitation, impersonation]
    2: pretending to be another person [syn: imposture,
       impersonation]
    3: imitating the mannerisms of another person [syn:
       impersonation, personation]