The Collaborative International Dictionary of English v.0.48:

Perfunctory \Per*func"to*ry\ (p[~e]r*f[u^][ng]k"t[-o]*r[y^]), a.
   [L. perfunctorius, fr. perfunctus dispatched, p. p. of
   perfungi to discharge, dispatch; per (see Per) + fungi to
   perform. See Function.]
   1. Done merely to get rid of a duty; performed mechanically
      and as a thing of rote; done in a careless and superficial
      manner; characterized by indifference; as, perfunctory
      admonitions; a perfunctory greeting. --Macaulay.
      [1913 Webster]

   2. Hence: Mechanical; indifferent; listless; careless.
      "Perfunctory in his devotions." --Sharp.
      [1913 Webster]

WordNet (r) 3.0 (2006):

perfunctory
    adj 1: hasty and without attention to detail; not thorough; "a
           casual (or cursory) inspection failed to reveal the
           house's structural flaws"; "a passing glance";
           "perfunctory courtesy" [syn: casual, cursory,
           passing(a), perfunctory]
    2: as a formality only; "a one-candidate pro forma election"
       [syn: pro forma, perfunctory]

Moby Thesaurus II by Grady Ward, 1.0:

120 Moby Thesaurus words for "perfunctory":
   Laodicean, airy, apathetic, at odds, ataractic, automatic, averse,
   backward, balking, balky, blase, businesslike, careless, casual,
   cold, cool, cursory, degage, devil-may-care, differing, dilatory,
   disagreeing, disinclined, disinterested, dismissive, disobedient,
   dispassionate, disregardant, disregardful, distant, easygoing,
   fervorless, fleeting, flippant, forced, forgetful, formal,
   fractious, free and easy, grudging, halfhearted, hasty, heedless,
   hurried, impersonal, inattentive, inconsiderate, incurious,
   indifferent, indisposed, indocile, inexcitable, insouciant,
   involuntary, lackadaisical, laggard, lazy, listless, loath,
   lukewarm, mechanical, mindless, mutinous, negligent, neuter,
   neutral, nonchalant, oblivious, offhand, opposed, pococurante,
   recalcitrant, reckless, refractory, regardless, reluctant, removed,
   renitent, resistant, respectless, restive, routine, rushed,
   sketchy, slipshod, slovenly, slow, slow to, spotty, standard,
   stock, sulky, sullen, superficial, tactless, tepid, thoughtless,
   turned-off, unanxious, unaware, unconcerned, unconsenting,
   undiplomatic, undiscriminating, unenthusiastic, unheedful,
   unheeding, uninterested, uninvolved, unmindful, unprepared,
   unready, unsolicitous, untactful, unthinking, unwilling, unzealous,
   usual, wooden, zealless