Constitutional Convention (political meeting)

A constitutional convention is a gathering for the purpose of writing a new constitution or revising an existing constitution. Members of a constitutional convention (sometimes referred to as "delegates to" a constitutional convention) are often elected by popular vote. The resulting constitutional frame of government is often subjected to a popular vote via referendum before it enters into force.

Examples of constitutional conventions to form or revise the constitution of a nation include:

Constitutional conventions have also been used by constituent states of federations — such as the individual states of the United States — to create, replace, or revise their own constitutions. Several US States have held multiple conventions over the years to change their particular state's constitutions.

...
Wikipedia