presupposition Definition

1. To take for granted; to assume as true.

Thesaurus: suppose, presume, assume, take for granted.
2. To require as a necessary condition; to imply the existence of something.

Thesaurus: posit, postulate, premise, accept, imply, consider.

Something assumed as true or required as a necessary condition
Thesaurus: supposition, presumption, assumption, belief, theory, preconception, hypothesis, premise.