The Collaborative International Dictionary of English v.0.48:

Historiographer \His*to`ri*og"ra*pher\
   (h[i^]s*t[=o]`r[i^]*[o^]g"r[.a]*f[~e]r), n. [L.
   historiographus, Gr. "istoriogra`fos; "istori`a history +
   gra`fein to write: cf. F. historiographe.]
   An historian; a writer of history; especially, one appointed
   or designated to write a history; also, a title bestowed by
   some governments upon historians of distinction.
   [1913 Webster]

WordNet (r) 3.0 (2006):

historiographer
    n 1: a person who is an authority on history and who studies it
         and writes about it [syn: historian, historiographer]