I've looked for and read many definitions of what "outsider art" is. Some call it naive art, others call it folk or primitive art. It can be tramp art or prison art. Others say it is simply art made by those are self-taught and outside the traditional art world.
No where have I seen what I think defines it. Outsider art is art made by those who have to create and will create out of any materials at hand. There is a need to create in each of us and for outsider artists, this need is profound and cannot be denied. The pure human impulse to create is the essence.
The art that is made is visionary and made to fulfill a need in oneself, not the needs of others. It is personal. It is honest. It is original. It can be whimsical, strange, or disturbing. And, always, in its own way, it is very powerful.