The Collaborative International Dictionary of English v.0.48:

Picayune \Pic`a*yune"\, n. [From the language of the Caribs.]
   A small coin of the value of six and a quarter cents. See
   Fippenny bit. [Local, U.S.]
   [1913 Webster]
   [1913 Webster]

WordNet (r) 3.0 (2006):

picayune
    adj 1: (informal) small and of little importance; "a fiddling
           sum of money"; "a footling gesture"; "our worries are
           lilliputian compared with those of countries that are at
           war"; "a little (or small) matter"; "a dispute over
           niggling details"; "limited to petty enterprises";
           "piffling efforts"; "giving a police officer a free meal
           may be against the law, but it seems to be a picayune
           infraction" [syn: fiddling, footling, lilliputian,
           little, niggling, piddling, piffling, petty,
           picayune, trivial]

Moby Thesaurus II by Grady Ward, 1.0:

147 Moby Thesaurus words for "picayune":
   a continental, a curse, a damn, a darn, a hoot, bagatelle, bauble,
   bean, bibelot, bickering, bit, brass farthing, button, captious,
   caviling, cent, choplogic, curio, cursory, depthless, detailed,
   equivocatory, evasive, exact, farce, farthing, feather, few, fig,
   finicky, fleabite, folderol, footling, fribble, frippery, full,
   fussy, gaud, gewgaw, gimcrack, hair, hairsplitting, halfpenny,
   hedging, hill of beans, immateriality, inconsequence, inconsequent,
   inconsequential, inconsequentiality, inconsiderable,
   inconsiderableness, indifference, ineffectuality, inferiority,
   insignificance, insignificant, irrelevance, jerkwater, jest, joke,
   kickshaw, knickknack, knickknackery, little, littleness,
   logic-chopping, low, low priority, marginality, meager, measly,
   meticulous, miniature, minikin, minute, mockery, molehill,
   negligibility, negligible, nice, niggling, nit-picking,
   no great shakes, one-horse, paltering, paltry, particular,
   peppercorn, pettifogging, pettiness, petty, picayunish,
   picayunishness, piddling, piffling, pin, pinch of snuff, pinprick,
   pokiness, poky, precise, puniness, punk, puny, pussyfooting,
   quibbling, rap, red cent, row of pins, rush, secondariness,
   shallow, shit, short, shuffling, skin-deep, slightness, small,
   small-beer, small-time, smallness, snap, sneeshing, sou, special,
   specific, straw, superficial, tinhorn, tiny, toy, trichoschistic,
   trifle, trifling, trinket, trivial, triviality, tuppence,
   two cents, two-bit, two-by-four, twopence, unimportance,
   unimpressiveness, unnoteworthiness, whim-wham



U.S. Gazetteer Places (2000):

Picayune, MS -- U.S. city in Mississippi
   Population (2000):    10535
   Housing Units (2000): 4568
   Land area (2000):     11.763019 sq. miles (30.466079 sq. km)
   Water area (2000):    0.040986 sq. miles (0.106154 sq. km)
   Total area (2000):    11.804005 sq. miles (30.572233 sq. km)
   FIPS code:            57160
   Located within:       Mississippi (MS), FIPS 28
   Location:             30.528089 N, 89.680182 W
   ZIP Codes (1990):     39466
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Picayune, MS
    Picayune