The Collaborative International Dictionary of English v.0.48:

Stuffy \Stuff"y\, a.
   1. Stout; mettlesome; resolute. [Scot.] --Jamieson.
      [1913 Webster]

   2. Angry and obstinate; sulky. [U. S.]
      [1913 Webster]

   3. Ill-ventilated; close.
      [1913 Webster]

WordNet (r) 3.0 (2006):

stuffy
    adj 1: lacking fresh air; "a dusty airless attic"; "the
           dreadfully close atmosphere"; "hot and stuffy and the air
           was blue with smoke" [syn: airless, close, stuffy,
           unaired]
    2: excessively conventional and unimaginative and hence dull;
       "why is the middle class so stodgy, so utterly without a
       sense of humor?"; "a stodgy dinner party" [syn: stodgy,
       stuffy]
    3: affected with a sensation of stoppage or obstruction; "a
       stuffy feeling in my chest"

Moby Thesaurus II by Grady Ward, 1.0:

255 Moby Thesaurus words for "stuffy":
   Quakerish, Victorian, accordant, airless, anal, arid, arrogant,
   authoritarian, bad, bad-smelling, barren, bigot, bigoted, blah,
   blank, bloated, bloodless, bombastic, borne, bourgeois, breathless,
   breezeless, cantankerous, censorious, characterless, close, closed,
   cold, colorless, compulsive, concordant, conformist, constricted,
   contrary, conventional, corresponding, cramped, creedbound,
   cross-grained, dead, deaf, deaf to reason, demure, difficult,
   dismal, draggy, drearisome, dreary, dry, dryasdust, dull, dusty,
   earthbound, effete, elephantine, empty, etiolated, fade, fanatical,
   fecal, fetid, flat, flatulent, fogyish, formal, formalistic, foul,
   froward, frowsty, frowsy, frowy, frowzy, fuddy-duddy, fulsome,
   funky, fusty, gamy, gassy, genteel, grandiloquent, graveolent,
   harmonious, heavy, hidebound, high, ho-hum, hollow, humdrum, humid,
   ill-smelling, ill-ventilated, illiberal, important, in accord,
   in keeping, in line, in step, inane, inexcitable, infecund,
   infertile, inflated, insipid, insular, irascible, jejune, kosher,
   leaden, lifeless, literal, little, little-minded, low-spirited,
   magisterial, malodorous, mean, mean-minded, mean-spirited,
   mephitic, miasmal, miasmic, mid-Victorian, mildewed, mildewy,
   moldy, mouldy, muggy, mundane, musty, narrow, narrow-hearted,
   narrow-minded, narrow-souled, narrow-spirited, nearsighted,
   nidorous, noisome, noxious, odorous, offensive, old-fashioned,
   old-fogy, old-fogyish, old-maidish, olid, oppressive, ornery,
   orthodox, overmodest, pale, pallid, parochial, pedantic,
   pedestrian, perverse, petty, plastic, plodding, pointless, poky,
   pompous, ponderous, pontifical, precisianistic, priggish, prim,
   prissy, proper, prosaic, prosing, prosy, provincial, prudish,
   puffy, purblind, puritanical, putrid, rancid, rank,
   ravaged with age, reasty, reasy, reechy, reeking, reeky, repulsive,
   rigid, rotten, sanctimonious, self-important, senile, shortsighted,
   slow, small, small-minded, smellful, smelling, smelly, smug,
   solemn, spiritless, square, stagnant, staid, stale, stenchy,
   sterile, sticky, stiff, stiff-necked, stifling, stilted, stinking,
   stodgy, stolid, straight, strait-laced, straitlaced, strong,
   suffocating, sulfurous, sulky, sullen, sultry, superficial,
   swollen, tasteless, tedious, thick, traditionalist, tumid, turgid,
   uncatholic, uncharitable, unfanciful, ungenerous, unideal,
   unimaginative, uninspired, uninventive, unliberal, unlively,
   unoriginal, unpoetic, unromantic, unromanticized, unvented,
   unventilated, uptight, vapid, vile, wayward, windless, wooden,
   wrongheaded