postulate

Concise Oxford English Dictionary © 2008 Oxford University Press:
postulate

▶verb /ˈpɒstjʊleɪt/ 

• 1 suggest or assume the existence, fact, or truth of (something) as a basis for reasoning, discussion, or belief.

• 2 (in ecclesiastical law) nominate or elect to an ecclesiastical office subject to the sanction of a higher authority.

▶noun /ˈpɒstjʊlət/ a thing postulated.

– derivatives
postulation noun,
postulator noun.

– origin ME: from L. postulat-, postulare ‘ask’.