The Collaborative International Dictionary of English v.0.48:

Banal \Ban"al\, a. [F., fr. ban an ordinance.]
   Commonplace; trivial; hackneyed; trite.
   [1913 Webster]

WordNet (r) 3.0 (2006):

banal
    adj 1: repeated too often; overfamiliar through overuse;
           "bromidic sermons"; "his remarks were trite and
           commonplace"; "hackneyed phrases"; "a stock answer";
           "repeating threadbare jokes"; "parroting some timeworn
           axiom"; "the trite metaphor `hard as nails'" [syn:
           banal, commonplace, hackneyed, old-hat,
           shopworn, stock(a), threadbare, timeworn,
           tired, trite, well-worn]

Moby Thesaurus II by Grady Ward, 1.0:

72 Moby Thesaurus words for "banal":
   asinine, average, back-number, bewhiskered, bland, bromidic,
   central, cliched, common, commonplace, corny, cut-and-dried,
   everyday, fade, familiar, fatuous, flat, fusty, hackney, hackneyed,
   hoary, humdrum, intermediary, intermediate, jejune, mean, medial,
   median, mediocre, medium, middle-of-the-road, middling,
   milk-and-water, moderate, moth-eaten, musty, namby-pamby, normal,
   old, old hat, ordinary, pedestrian, petty, platitudinous, routine,
   sapless, set, silly, simple, square, stale, standard, stereotyped,
   stock, threadbare, timeworn, tired, trite, trivial, truistic,
   unimaginative, unoriginal, usual, vapid, warmed-over, waterish,
   watery, well-known, well-worn, wishy-washy, worn, worn thin