The Collaborative International Dictionary of English v.0.48:

Anachronism \An*ach"ro*nism\, n. [Gr. 'anachronismo`s, fr.
   'anachroni`zein to refer to a wrong time, to confound times;
   'ana` + chro`nos time: cf. F. anachronisme.]
   A misplacing or error in the order of time; an error in
   chronology by which events are misplaced in regard to each
   other, esp. one by which an event is placed too early;
   falsification of chronological relation.
   [1913 Webster]

WordNet (r) 3.0 (2006):

anachronism
    n 1: something located at a time when it could not have existed
         or occurred [syn: anachronism, mistiming, misdating]
    2: an artifact that belongs to another time
    3: a person who seems to be displaced in time; who belongs to
       another age