The missing word is RATIFICATION. The states met for the approval, confirmation, and ratification of a new constitution.
Ratification refers to a principal's approval of an act of its agent that does not have the authority to bind the principal legally. Ratification is considered the international act in which a state shows its consent to be bound to a treaty if the parties intended to indicate their consent by such an act.
The answer that would best complete the given statement above is the term RATIFICATION. So here is the complete one. <span>The states met for the approval, confirmation, and RATIFICATION of a new constitution. Hope this answers your question. Have a great day ahead!</span>