Kenneth G. Wilson (1923–). The Columbia Guide to Standard American English. 1993.
epic (adj., n.)
The word’s basic meaning is “a kind of long narrative heroic poem, such as The Iliad, The Aeneid, or Beowulf,” but our penchant for hyperbole has made us apply it today to novels and motion pictures with any sort of claim to gigantic scale, historical importance, or simply monumentalism, however defined. Then by functional shift we create the corresponding adjective, epic. Most use of epic is cliché nowadays—and so hyperbolic as to be nearly meaningless—but in its original senses it still can serve us well.
