Which of these is the best definition of the word "postulate"?

The best definition of the word "postulate" is "claim." A postulate is a statement or proposition that is assumed to be true without proof, serving as a basis for further reasoning or argument. It is a claim that is put forward as a starting point for a line of reasoning or investigation. "Disagree," "gather," and "move" do not accurately capture the meaning of "postulate."