1 The fundamental and organic laws and principles of a country or state that create a system of government and provides a basis against which the validity of all other laws is determined. 2 The fundamental rules governing an association. Constitution.The Constitution of the United States, written in 1787 and put into effect in 1789. unwritten constitution. The body of fundamental and organic laws and principles contained in a series of statutes, court decisions, governmental proclamations, an...