/ ˌpriːsʌpəˈzɪʃn; NAmE / noun
[ C , U ] ( formal ) something that you believe to be true and use as the beginning of an argument even though it has not been proved; the act of believing it is true
SYN assumption :
theories based on presupposition and coincidence
••
WORD ORIGIN
mid 16th cent.: from medieval Latin praesuppositio(n-) , from the verb praesupponere , from prae before + supponere place under (from sub- from below + ponere to place).