epigraph (n.) Look up epigraph at Dictionary.com
1620s, "inscription on a building, statue, etc.," from Greek epigraphe "an inscription," from epigraphein "to write on," from epi "on" (see epi-) + graphein "to write" (see -graphy). Sense of "motto; short, pithy sentence at the head of a book or chapter" first recorded in English 1844.