The Collaborative International Dictionary of English v.0.48:

Commonplace \Com"mon*place`\, a.
   Common; ordinary; trite; as, a commonplace person, or
   observation.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Commonplace \Com"mon*place`\, n.
   1. An idea or expression wanting originality or interest; a
      trite or customary remark; a platitude.
      [1913 Webster]

   2. A memorandum; something to be frequently consulted or
      referred to.
      [1913 Webster]

            Whatever, in my reading, occurs concerning this our
            fellow creature, I do never fail to set it down by
            way of commonplace.                   --Swift.
      [1913 Webster]

   Commonplace book, a book in which records are made of
      things to be remembered.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Commonplace \Com"mon*place`\, v. t.
   To enter in a commonplace book, or to reduce to general
   heads. --Felton.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Commonplace \Com"mon*place`\, v. i.
   To utter commonplaces; to indulge in platitudes. [Obs.]
   --Bacon.
   [1913 Webster]

WordNet (r) 3.0 (2006):

commonplace
    adj 1: completely ordinary and unremarkable; "air travel has now
           become commonplace"; "commonplace everyday activities"
    2: not challenging; dull and lacking excitement; "an unglamorous
       job greasing engines" [syn: commonplace, humdrum,
       prosaic, unglamorous, unglamourous]
    3: 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]
    n 1: a trite or obvious remark [syn: platitude, cliche,
         banality, commonplace, bromide]

Moby Thesaurus II by Grady Ward, 1.0:

209 Moby Thesaurus words for "commonplace":
   Attic, Babbittish, Philistine, Spartan, abstraction, accustomed,
   ascetic, austere, average, back-number, bald, banal, banality,
   bare, baseborn, below the salt, bewhiskered, bourgeois, bromide,
   bromidic, campy, candid, chaste, chestnut, classic, classical,
   cliche, cliched, cockney, common, commonly known,
   commonplace expression, conventional, corn, corny, current,
   customary, cut-and-dried, direct, dry, dull, everyday, fade,
   familiar, familiar tune, flat, frank, fusty, garden,
   garden-variety, general, general idea, generalization,
   generalized proposition, glittering generality, habitual, hackney,
   hackneyed, hackneyed expression, hackneyed saying, high-camp,
   homely, homespun, household, humble, humdrum, inanity, insipid,
   kitschy, lean, lieu commun, locus communis, low, low-camp, lowborn,
   lowbred, lowly, matter-of-fact, mean, middle-class, moth-eaten,
   mundane, musty, natural, neat, no great shakes, nonclerical,
   nondescript, normal, normative, notorious, old hat, old joke,
   old saw, old song, old story, open, ordinary, overworked,
   pedestrian, plain, plain-speaking, plain-spoken, plastic,
   platitude, platitudinous, plebeian, poetryless, pop, popular,
   predominating, prescriptive, prevailing, prevalent, prosaic,
   prosaicism, prosaism, prose, prosing, prosy, proverbial, public,
   pure, pure and simple, regular, regulation, reiteration,
   retold story, rubber stamp, rude, run-of-mine, run-of-the-mill,
   rustic, set, severe, shabby-genteel, shallowness, shibboleth,
   shopworn, simple, simple-speaking, sober, spare, square, stale,
   standard, stark, stereotype, stereotyped, stereotyped saying,
   stock, straightforward, suburban, sweeping statement, tag,
   talked-about, talked-of, third-estate, threadbare, timeworn, tired,
   tired cliche, tiresome, trite, trite saying, triteness, triticism,
   truism, truistic, twice-told tale, typical, unadorned, unaffected,
   unembellished, uneventful, unexceptional, ungenteel, unidealistic,
   unimaginative, unimpassioned, universal, universally admitted,
   universally recognized, unnoteworthy, unoriginal, unpoetic,
   unpoetical, unremarkable, unromantic, unspectacular, unvarnished,
   usual, vapid, vernacular, vulgar, warmed-over, well-kenned,
   well-known, well-recognized, well-understood, well-worn,
   widely known, wishy-washiness, wonted, workaday, workday, worn,
   worn thin, worn-out