Merriam-Webster Collegiate Dictionary - congregational

 adjective  Date: 1639  1. of or relating to a congregation  2. capitalized of or relating to a body of Protestant churches deriving from the English Independents of the 17th century and affirming the essential importance and the autonomy of the local congregation  3. of or relating to church government placing final authority in the assembly of the local congregation  • ~ism noun, often capitalized  • ~ist noun or adjective, often capitalized