the.com/postulate

means To assume something as true without proof, in order to use it as the starting point for an argument or theory.

from From Latin postulare, 'to demand or request' — the same root gives us 'postulant,' someone petitioning to join a religious order. A postulate is literally a demand you make of your audience: grant me this, and I'll build the rest. Medieval scholars used it for a proposition requested or claimed without proof, and by the time Euclid's geometry was being translated and taught, 'postulate' had settled into its modern sense — the unprovable favor you ask for before the real argument begins.