Naive art

term for the amateurish approach to artworks, free from established styles with childlike appearance, bright colors and detailed execution - became popular in the early twentieth century and influenced many modernist painters - sometimes referred as primitive art, folk art , outsider art - the german term is Sonntagsmaler 

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A condescending reference to untrained 20th Century painters.

Artwork that is produced by artists without formal training. Probably the best-known artist of this type is Grandma Moses. The style is generally childlike and innocent, but will have an unusual sensitive touch and a natural understanding of composition and spatial organization. This style should not be confused with folk art. Folk art contains functional forms that are specific to a culture.