The Collaborative International Dictionary of English v.0.48:

Superficial \Su`per*fi"cial\, a. [L. superficialis: cf. F.
   superficiel. See Superficies.]
   1. Of or pertaining to the superficies, or surface; lying on
      the surface; shallow; not deep; as, a superficial color; a
      superficial covering; superficial measure or contents;
      superficial tillage.
      [1913 Webster]

   2. Reaching or comprehending only what is obvious or
      apparent; not deep or profound; shallow; -- said
      especially in respect to study, learning, and the like;
      as, a superficial scholar; superficial knowledge.
      [1913 Webster]

            This superficial tale
            Is but a preface of her worthy praise. --Shak.
      [1913 Webster]

            He is a presumptuous and superficial writer.
                                                  --Burke.
      [1913 Webster]

            That superficial judgment, which happens to be right
            without deserving to be so.           --J. H.
                                                  Newman.
      [1913 Webster] -- Su`per*fi"cial*ly, adv. --
      Su`per*fi"cial*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

superficial
    adj 1: concerned with or comprehending only what is apparent or
           obvious; not deep or penetrating emotionally or
           intellectually; "superficial similarities"; "a
           superficial mind"; "his thinking was superficial and
           fuzzy"; "superficial knowledge"; "the superficial report
           didn't give the true picture"; "only superficial
           differences" [ant: profound]
    2: of, affecting, or being on or near the surface; "superficial
       measurements"; "the superficial area of the wall"; "a
       superficial wound"
    3: of little substance or significance; "a few superficial
       editorial changes"; "only trivial objections" [syn:
       superficial, trivial]

Moby Thesaurus II by Grady Ward, 1.0:

208 Moby Thesaurus words for "superficial":
   3-D, airy, amateur, amateurish, ankle-deep, apparent, appearing,
   arid, asinine, barren, birdbrained, birdwitted, blah, blank,
   bloodless, catchpenny, characterless, cold, colorless,
   conventionalized, cortical, cosmetic, critical, cubic, cursory,
   dabbling, dead, depthless, dilettante, dilettantish, dimensional,
   dismal, draggy, drearisome, dreary, dry, dryasdust, dull, dusty,
   effete, elephantine, empty, epidermal, epidermic, etiolated,
   exomorphic, expeditious, exterior, external, extrinsic, fade,
   fatuous, featherbrained, festinate, feverish, few, flat, flighty,
   flimsy, fluffy, flying, foolish, footling, formal, formalist,
   formalistic, formulary, fourth-dimensional, fribble, fribbling,
   fringe, frivolous, frothy, furious, futile, general, half-assed,
   half-baked, half-cocked, hasty, heavy, ho-hum, hollow, hurried,
   idle, immature, immediate, impersonal, inane, inconsequential,
   inconsiderable, inexcitable, insignificant, insipid, instant,
   insubstantial, jejune, knee-deep, last-minute, leaden, legalistic,
   lifeless, light, little, low, low-spirited, meager, meaningless,
   miniature, negligible, no great shakes, nominal, not deep,
   nugacious, nugatory, on the spot, on the surface, open, ostensible,
   otiose, out, outer, outermost, outlying, outmost, outside,
   outstanding, outward, outward-facing, pale, pallid, passing,
   pedantic, pedestrian, perfunctory, peripheral, petty, picayune,
   picayunish, plodding, pointless, poky, ponderous, prompt,
   proportional, public, quick, roundabout, sciolistic, seeming,
   shallow, shallow-headed, shallow-minded, shallow-pated,
   shallow-rooted, shallow-witted, shoal, short, silly, sketchy,
   skin-deep, slap-bang, slapdash, slender, slight, slow, small,
   smattering, snap, solemn, sophomoric, space, space-time, spatial,
   spatiotemporal, speedy, spherical, spiritless, stereoscopic,
   sterile, stiff, stodgy, stuffy, stylized, surface, swift,
   tasteless, tedious, thin, three-dimensional, tiny, trifling, trite,
   trivial, two-dimensional, uncritical, unimportant, unlively,
   unprofound, urgent, vacuous, vain, vapid, visible, volatile,
   volumetric, windy, wooden