501(c)(3)

Etymology
From the section of the U.S. federal tax code.

Noun

 * 1)  An organization that complies with section 501(c)(3) of the U.S. federal tax code. A non-profit organization exempt from some federal income taxes, due to being dedicated to charitable, religious, educational, scientific, public safety, promotion of amateur sport at the national or international level, prevention of cruelty to women or children or animals, or literary purposes.