The Collaborative International Dictionary of English v.0.48:

Epigraph \Ep"i*graph\, n. [Gr. ?, fr. ?: cf. F. ['e]pigraphe.
   See Epigram.]
   1. Any inscription set upon a building; especially, one which
      has to do with the building itself, its founding or
      dedication.
      [1913 Webster]

   2. (Literature) A citation from some author, or a sentence
      framed for the purpose, placed at the beginning of a work
      or of its separate divisions; a motto. Epigraphic

WordNet (r) 3.0 (2006):

epigraph
    n 1: a quotation at the beginning of some piece of writing
    2: an engraved inscription

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "epigraph":
   banner, banner head, caption, catchword, device, drop head,
   dropline, epithet, hanger, head, heading, headline, initialing,
   inscription, jump head, legend, lettering, motto, overline, rubric,
   running head, running title, scarehead, screamer, slogan, spread,
   spreadhead, streamer, subhead, subheading, subtitle,
   superscription, tag line, title, title page, transcription,
   transliteration, watchword