The Collaborative International Dictionary of English v.0.48:

Homily \Hom"i*ly\, n.; pl. Homilies. [LL. homilia, Gr. ?
   communion, assembly, converse, sermon, fr. ? an assembly, fr.
   ? same; cf. ? together, and ? crowd, cf. ? to press: cf. F.
   hom['e]lie. See Same.]
   1. A discourse or sermon read or pronounced to an audience; a
      serious discourse. --Shak.
      [1913 Webster]

   2. A serious or tedious exhortation in private on some moral
      point, or on the conduct of life.
      [1913 Webster]

            As I have heard my father
            Deal out in his long homilies.        --Byron.
      [1913 Webster]

   Book of Homilies. A collection of authorized, printed
      sermons, to be read by ministers in churches, esp. one
      issued in the time of Edward VI., and a second, issued in
      the reign of Elizabeth; -- both books being certified to
      contain a "godly and wholesome doctrine."
      [1913 Webster]

WordNet (r) 3.0 (2006):

homily
    n 1: a sermon on a moral or religious topic [syn: homily,
         preachment]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "homily":
   article, assignment, causerie, chalk talk, descant, discourse,
   discussion, disquisition, dissertation, essay, etude, examination,
   excursus, exercise, exposition, feature, first approach, harangue,
   homework, instruction, introductory study, lecture,
   lecture-demonstration, lesson, lucubration, memoir, monograph,
   moral, moral lesson, morality, moralization, morceau, note,
   object lesson, outline, pandect, paper, paragraph, piece,
   preachification, preaching, preachment, prelection,
   preliminary study, prolegomenon, recital, recitation,
   religious discourse, research paper, screed, sermon, sermonette,
   set task, sketch, skull session, special article, study, survey,
   talk, task, teaching, term paper, theme, thesis, tract, tractate,
   travelogue, treatise, treatment