The Collaborative International Dictionary of English v.0.48:

Dossier \Dos`sier"\ (d[-o]s`sy[asl]"; E. d[o^]s"s[i^]*[~e]r), n.
   [F., back of a thing, bulging bundle of papers, fr. dos
   back.]
   A bundle containing the papers in reference to some matter.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

dossier
    n 1: a collection of papers containing detailed information
         about a particular person or subject (usually a person's
         record)