There is disagreement within the art community regarding strict definitions of this genre of art, so the definitions below are meant to serve only as a starting point for discussion. It arrived in the early twentieth century as “art brut,” when European psychiatrists began to define the various forms of creative expression that exist outside the boundaries of “fine art.” Offshoots have surfaced ever since. As Rebecca Hoffberger, the founder of the American Visionary Art Museum in Baltimore, succinctly describes the drive behind the art, “When it can’t come out with words, it comes out in objects.”

The following are my simple and loose interpretations to serve as a starting point:

Art Brut—(translates to “raw art”) It was influenced by Hans Prinzhorn’s book, Artistry of the Mentally Ill; French artist Jean Dubuffet’s original term for people working outside the influences of established art boundaries. The term is only to be used with works from within the Collection de l’Art Brut at Lausanne (examples include Adolph Wolfii, and American artists Martin Ramirez, Henry Darger and Ted Gordon).

Outsider Art—Originally an English equivalent to Art Brut, the term was coined by Roger Cardinal in the late 1960s, broadening the narrow scope of the Art Brut definition to include art that is produced by untrained artists who are unaware of its classic definition, such as those cut off from mainstream society. The term has been designated by academia, not by the artists themselves, and is thought by some to be a bit derogatory in that term implies that the artists aren’t “inside” the art world. (examples include ex-slave Bill Traylor, Burgess Dulaney, and Simon Rodia).

Folk, Contemporary Folk, or Self-taught Art—Usually these artists are self-taught and there is crossover from Outsider Art. Originally, the phrase pertained to crafts and practical objects of the colonial days that were both visually appealing and practical in craft. Oft times the art is passed among family or a community. The contemporary meaning has been stretched to include the less-than-practical, including hubcap fences and chain saw art. (examples include Thornton Dial, Homer Green, Sam Doyle, and Mose Tolliver).

Visionary or Intuitive Art—A subset of Outsider Art, usually these artists have experienced a vision or divine guidance that influences their art. These are “safe” umbrella terms that are more encompassing much of the work described, as well as art of the third world. (examples include William Thomas Thompson, Howard Finster, and Jessie and Ronald Cooper, Missionary Mary Proctor, Annie Wellborn.)

Visionary, Folk, Vernacular, or Grassroots Environments— These environments—homes, parks, gardens, or the indescribable, are often built by visionaries or outsider folk artists. At times, the builders are more integrated into the mainstream. (examples include S.P. Dinsmoor’s Garden of Eden, Tom Every’s Forevertron, Leonard Knight’s Salvation Mountain, and Simon Rodia’s Watts Towers).

To learn more about outsider art:
Raw Vision’s web site is an excellent resource to get you started.
http://www.rawvision.com/outsiderart/whatisoa.html