The Collaborative International Dictionary of English v.0.48:

Bohemian \Bo*he"mi*an\, a.
   1. Of or pertaining to Bohemia, or to the language of its
      ancient inhabitants or their descendants. See Bohemian,
      n., 2.
      [1913 Webster]

   2. Of or pertaining to a social gypsy or "Bohemian" (see
      Bohemian, n., 3); vagabond; unconventional; free and
      easy. [Modern]
      [1913 Webster]

            Hers was a pleasant Bohemian life till she was five
            and thirty.                           --Blackw. Mag.
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            Artists have abandoned their Bohemian manners and
            customs nowadays.                     --W. Black.
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   Bohemian chatterer, or Bohemian waxwing (Zool.), a small
      bird of Europe and America (Ampelis garrulus); the
      waxwing.

   Bohemian glass, a variety of hard glass of fine quality,
      made in Bohemia. It is of variable composition, containing
      usually silica, lime, and potash, rarely soda, but no
      lead. It is often remarkable for beauty of color.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Bohemian \Bo*he"mi*an\, n.
   1. A native of Bohemia.
      [1913 Webster]

   2. The language of the Czechs (the ancient inhabitants of
      Bohemia), the richest and most developed of the dialects
      of the Slavic family.
      [1913 Webster]

   3. A restless vagabond; -- originally, an idle stroller or
      gypsy (as in France) thought to have come from Bohemia; in
      later times often applied to an adventurer in art or
      literature, of irregular, unconventional habits,
      questionable tastes, or free morals. [Modern]
      [1913 Webster]

   Note: In this sense from the French boh['e]mien, a gypsy;
         also, a person of irregular habits.
         [1913 Webster]

               She was of a wild, roving nature, inherited from
               father and mother, who were both Bohemians by
               taste and circumstances.           --Thackeray.
         [1913 Webster]

WordNet (r) 3.0 (2006):

Bohemian
    adj 1: of or relating to Bohemia or its language or people
    2: unconventional in especially appearance and behavior; "a
       bohemian life style"
    n 1: a member of a people with dark skin and hair who speak
         Romany and who traditionally live by seasonal work and
         fortunetelling; they are believed to have originated in
         northern India but now are living on all continents (but
         mostly in Europe, North Africa, and North America) [syn:
         Gypsy, Gipsy, Romany, Rommany, Romani, Roma,
         Bohemian]
    2: a native or inhabitant of Bohemia in the Czech Republic
    3: a nonconformist writer or artist who lives an unconventional
       life

Moby Thesaurus II by Grady Ward, 1.0:

75 Moby Thesaurus words for "Bohemian":
   Arab, Bedouin, Romany, Zigeuner, affable, beat, beatnik, breakaway,
   casual, cordial, degage, deviant, dissenter, dropout, easy,
   easygoing, eccentric, familiar, far out, flower child, folksy,
   freak, free and easy, fringy, gracious, gypsy, haymish, heretic,
   heretical, heterodox, hippie, homely, homey, iconoclast, informal,
   irregular, kinky, loose, maverick, misfit, natural, nomad,
   nonconformist, nonjuror, not cricket, not done, not kosher,
   offbeat, offhand, offhanded, original, plain, recusant, relaxed,
   sectarian, sectary, simple, sociable, swinger, tzigane,
   ugly duckling, unaffected, unassuming, unceremonious, unconforming,
   unconformist, unconstrained, unconventional, unfashionable,
   unofficial, unorthodox, unstudied, way out, yippie, zingaro